I've checked the reference line orange/white from tps and get 5v while plugged into tps. Tried a new coil, tried a new icm, and tried to unplug a jumper plug right off the icm connector (said to give the computer control of the spark so says scanner Danner on YouTube) all with same results.

The idle is mostly perfect but occasionally it will dip like 500rpm quick and jump back up. It does this a couple times Till it warms up and then its rock solid. Any throttle applied and it will start to rise and then drop like a rock, if you let off fast enough the truck will catch itself.

I have checked the fuel filter and fuel pump and even the return line to make sure fuel is making it all the way through the system and it has full flow. This really seemed like electrical in nature but I thought I'd check the fuel system anyway.

Only thing left seems to be the ecm. If that little jumper connector right at the icm connector is infact giving the ecm control over the coil, and the truck does the same exact thing whether that jumper is plugged in or not, am I correct in the logic that the ecm has an internal issue where it cant control the distributor timing advance for higher rpm, and I need a new ecm?

 

If you do not verify fuel pressure with a gauge 35-45 psi you are flying blind.
Must verify correct fuel press before moving on to anything else.

 

If your fuel side is okay then look at the AIR and unplug your MAF. Check here for more details.

 

no way to do that, i had my fuel pressure gauge ready to test the truck but there is no fuel service port that I can see. It really doesnt feel fuel related. The drop and snap back of the rpms is so fast it doesnt seem like fuel plus i forgot to mention that the truck puffs black smoke when restarting after dying meaning its dumping fuel in and not igniting. I would like to know the fuel pressure is steady but i just dont have a way to confirm it. I also took off and plugged the vacuum line from the fuel pressure regulator. Made no difference.

 

as far as I know there is no maf on this truck it's map based. I did take off the air intake hoses and ran the truck straight from the throttle body. No change.

 

If you have MAP instead, disconnect it and put your airbox and hose back and test drive for 5 minutes or so.

 

It wont drive at all as is. I can u hook map and try it but so far everything I've tried it dies when you rev it. Occasionally you can get it to go up to about 2.5k rpms if you are extremely carefully slow with the throttle pedal and then it cuts out and dies. Its basically not drivable its not even movable.

 

88 F150 4.9L - Fuel pressure specification as follows:
Key On Engine Off: 50-60psi
Key On Engine Running: 45-60psi

 

Ok so I do not see any Schrader valve aka service port on this fuel rail as I mentioned before. Anyone have a pic of where it is on an 88 f150 with 4.9l? I'd greatly appreciate it.

 

It will take me quite some time to get you the location diagram. In the meantime I have attached a few pdf for you to work on if needed. The MAP removal is the easiest test I brought up previously you should try first.