Truck is a 91 350 K1500

So i just bought this pickup and it wasnt running, my mechanic ended up replacing the spark plugs, battery, distributor, spark plug wires, coolant temp sensor and set the timing.

It will run damn near perfect after it has been warmed up, you can even turn it off for a few hours and restart it and it runs great

If you let it sit over night and start it in the morning, it runs very crappy.

Very rough idle with RPMs jumping around from 500-1500 and just backfiring, etc, if you give it some gas and keep it chugging for a couple minutes until it warms up it runs great again

Has anybody else had these type of issues before? Want to try and figure out what it is on my own before i send it back to my mechanic

I was thinking maybe the TPS or EGR sticking open, what do you guys think?

 

I would check the fuel pressure when doing a cold start up.

 

ok i will have to look into this

just out of curiosity, if it was a fuel pump issue would i see problems after its warmed up?

when its warmed up i have absolutely no issues, drives like new, no loss of power with acceleration or anything

 

It's a TBI..right?

 

check ( just replace - they are only $25) the IAC idle air control located on the left side of the throttle body. Also check the engine thermostat sensor. This is #1 most likely

 

Is the engine thermostat sensor the same as the coolant temp sensor? because my mechanic did replace that