So my 1991 E350 has been sluggish at acceleration but this starts happening after she warms up which is confusing the heck out of me. So as soon as I start her up and without truely warming up she drives great with what I feel is proper acceleration. But once she reach operating temp she becomes sluggish. Has anyone experienced this before?

 

We always inquire about past routine maintenance ,,,because , if for instance a fuel filter was never replaced, routine maintenance, could send you on a wild goose chase.

 

I probably should of included that information. So recently i have replaced the following"

Plugs
Wires
Coil
TPS
MAF
Fuel Filter
Fuel Pump
new exhaust

I do know the next thing i need to replace is the throttle cable as the end of my cable is frayed. So i don't know if that has anything to do with it but throwing that out there. Other then the sluggish acceleration once its warm she sounds and drives great!!

 

Let me maybe re-phrase the issue. I have better throttle response with the car at start up and once its at operating temp i lose that throttle response. Could i be looking at a dirty throttle body or a faulty TPS?

For additional history i have has a loss of power issue over the last two months and during that time she was backfiring but i have since fixed that issue. I don't know if i have build up in my throttle body that is a causing lack of power after she warms up or what? I have gutted my catalytic converter, new exhaust and no exhaust leaks. When she idles she purrs like a kitten and when i get good throttle response she drives great.

Suggestions on where to look next?

 

You already replaced quite a few components. Have you checked the most overlooked component: Engine Coolant Temp Sensor (ECT) yet?



Test the voltage and resistance first, don't just replace the sensor.

PCV valve is also an overlooked component, should be replaced every 30k miles, if you haven't changed that for a while.

 

what is interesting about that is i have noticed my engine temp running a little over 200 compared to around 185 its usually at. I don't know when that part was last replaced nor the PCV valve.

 

That coolant sensor is for the PCM, not for the gauge, that's why on the pic you see "for computer"
pcv valve is so inexpensive and should be replaced routinely.

 

I think i am going to try the PCV valve first and go from there. The Engine Coolant Temp sensor isn't very expensive either so i may just do both and see.

 

What does a PCV valve do you can search google easily and it's easier to replace. When you remove the old one be sure to shake it. The ECT is not difficult to replace but the coolant is going to spill when you remove the old one out. Even if you don't want to check the voltage and resistance you should remove just the electrical connector and clean first. The corrosion can cause false reading. Also don't forget to check your coolant level once a month. When it's low it can cause more problems than just your AC.