The reason I didn't replace the plugs is because they looked almost new. Just one was gapped wrong. I pulled the EGR valve and it looked new. I cleaned it up anyway and worked the plunger. Totally free.

I did discover something new today. I installed the new filter, but it still ran like crap. No water came out, just clean gas. It had recently been changed. I let it run for 10 minutes, shut it off for 10 minutes and cranked it back up and it ran perfect.

I then drove it to Pull-a-Part and spent a couple hours there. When I came back it was running poorly again. This time I just let it idle... Then after about 15 minutes it Suddenly smoothed out. So the conclusion is that it runs crappy when cold, smooth when warm. BTW, I replaced the MAP sensor with one from pull a part, no difference at all, so scratch that one off.

I guess I will have to order the 7 pin connector I need for the OBD2 reader unless that last clue helps.

 

Some of these things seem to take so long to find the answer, but we keep trying.
From what you are describing, when the engine is cold it runs poorly , but once it reaches operating temp it clears up.
It would seem that until the computer takes over the truck runs poorly.
The computer takes over and the engine runs fine.
Whatever is causing the problem is corrected by the computer when it takes over.
I believe the truck uses the OBD I system .
When you get the tester you can run the KOEO (key on engine off) test and it will probably direct you to the possible system causing the problem.
In the meantime I would look very carefully for any vacuum lines that may be off or cracked or missing.

 

Thanks for all the help and feedback. By the way, it is in E-350. I don't know if I explained well, but it turns out that this truck is an odd-ball 1995 which actually used obd2 but has a very strange 7 pin port, unlike the ones in your link. It is actually under the dash.

So the computer is taking over when it runs well? That's interesting. It must be compensating for something. But boy, when it runs good, it runs great! That part is encouraging.

On an unrelated note, I was getting quite a lot of clatter on the top end under high rpms. So I added a quart of Marvel Mystery Oil and I was absolutely amazed at how quickly the clatter went away! Wow! I have always loved that stuff. I will run it like that for a few days then change the oil. Like I said before, not sure how long it had been sitting.

 

Maintained a fleet of over 60 of those E350 s , they were a good truck and gave good service when maintained. Mileage was not the best ,but they were very dependable.
What size body does it have , 14, 16 ft ? If you plan to use it a lot keep a close eye on the front pads they give no warning until they cut into the rotors then its too late and it can get expensive.

 

I think it has a 14' box. It was listed as a 15' so I will have to measure it. Like I said, when it runs smooth it runs smooth but has a difficult time keeping up highway speeds... Maybe just a little worn out. 215k mi. Either that or it's geared real low. Around town it has plenty of pick up.

I'll keep an eye on the brakes, thanks for the heads up. We really bought it to move with. We are moving from NC to AZ and have a lot of business equipment we need to take. When we get there I don't necessarily want to unload immediately so this seemed like a good option, and cheap. Paid $1,600 and had to replace the drivers door and fender. ($100 from pull-a-part and did it myself... So glad they were almost all white LOL)

 

Not knowing your vehicle's maintenance history, some of the things I can recall that you might consider checking .
Lower ball joints
The most common engine problems were the water pump, EGR position sensor , then u-joints. If the trans has never had the fluid and filter changed might be a consideration before going on a long hot trip to AZ. Have a good trip !

 

EGR position sensor?... Hmmm... Wonder if that might be the trouble with it. The truck is very very tight driving, so I'm thinking the front end is in good shape, but I'll have a look. Transmission shifts perfectly with no hesitation or slippage. I'll have a feel of the U-joint. I have heard some clunkning sounds. Thanks for the tips.

 

off topic question, but you don't live in GA do you? specifically near the ellenwood/ stockbridge area? i ask because someone came to the store i work at (advance auto in ellenwood) with a very similar problem also with a box truck. if that was you, i'm with big guy who drives the old VW bug, if not, then never mind,

 

No, not me but if you figured it out what was wrong with that truck please tell me... LOL.

Still trying to track the problem and this is what I have done...

Pulled codes, it showed a bad EGR position sensor and a band Canister purge valve. (565)

-Replaced EGR position sensor
-Replaced Engine Coolant Temp sensor
-Thoroughly cleaned TB, IAC, TPS, EGR
-Tested TPS (good)
-Tested fuel pressure at idle, giving gas and with vac off (all good)
-Replaced Fuel filter
-Examined spark plugs (good)
-Replaced wires, cap & Rotor button
-Replaced bad vacuum lines

What is missing or disconnected are TAB and TAD, Air pump and canister purge valve is completely missing and port is plugged off.

 

Some guys because they don't understand how the system was designed to work will remove and disconnect some of the emission equip/controls thinking it will improve performance or didn't want to spend the money to correctly repair it.
The TAB & TAD are directly affected by the AIR pump. When the check valves in the AIR system burned through and repairs were not made to correct this, it would also burn up the AIR pump. The Ecm may be trying to operate the TAD and TAB through the vacuum lines which may not be connected to anything. The vacuum sources and controls need to be checked very thoroughly for any possible leaks which the ECM may be compensating for once it takes control. Is the vacuum diagram still present and able to be read on the hood?