Idle gets gradually worse after replacing distributor cap, rotor, plugs, and plug wires

[Das Hatt]

I bought a new IAC and that didn’t seem to fix the problem

You can't just install a new IAC and be done with it. There is a relearn procedure in the factory service manual. Did you perform this procedure after installing it?

 

[movietvet]

I bought a new IAC and that didn’t seem to fix the problem

Was that something you had already done before and forgot to share or did you just buy it? Did you clean the port area where the pintle works? Pics of what the old pintle and port looked like?

Have you checked for vacuum leaks?

 

[Joeyatwell5]

Was that something you had already done before and forgot to share or did you just buy it? Did you clean the port area where the pintle works? Pics of what the old pintle and port looked like?

Have you checked for vacuum leaks?

That was something i had already replaced in the past

 

[Joeyatwell5]

That was something i had already replaced in the past

Was that something you had already done before and forgot to share or did you just buy it? Did you clean the port area where the pintle works? Pics of what the old pintle and port looked like?

Have you checked for vacuum leaks?

I’m not really sure where I would be looking for the vacuum leaks

 

[Joeyatwell5]

So the timing is set around 9-10, it seems to idle decently but when you put it into gear and give it a bit of gas it seems to just die, any thoughts on what could be happening?

 

[GoToGuy]

IAC , EGR ?

 

[Joeyatwell5]

IAC , EGR ?

The iAC was recently replaced, I watched a YouTube video on how to set it, haven’t looked at the egr yet

 

[Joeyatwell5]

The iAC was recently replaced, I watched a YouTube video on how to set it, haven’t looked at the egr yet

Just replaced the egr, just to be safe but no luck on fixing the issue, any other ideas/ thoughts of what could be causing this?

 

[KY-N]

You don't say if your setting an SES code or not, I recently went though this with my 92' K3500, 454 and it had the exact same symptoms as yours. It would set a code that at first that could not be pull from the computer, I replaced the computer thinking that was the problem. Nope but I could pull the code at least I could pull the code, O2 sensor (ain't it always), replaced the O2 and it needed it since it looked like it was the OEM. Cleared the code ran it and it reset the code again, long story short, I ended up replacing EVERYTHING on the truck. Every sensor, all ignition parts, rebuilt the TBI, verified the fuel pressure, verified the wiring and grounds and every time it set the same code. In the end it turned out be the PO had installed a Hyperchip and even though I changed out the ECU, neither I nor a fellow who was suppose to be knowledgeable about this sort of thing recognized it for what it was. After removing the Hyperchip daughter board and reinstalling the OEM chip the truck ran fine for about 4 months then the same problem started up again. It took me 6 weeks but I finally found an ECU with chip from a 93' and replaced mine with it, just my luck this truck is equipped with and ECU and chip that was only used for a limited number of vehicles. Anyway the truck has been perfect ever since and actually gained a little over a mile per gallon of gas. I decided the Hyperchip must have done something the the OEM chip when it failed.

Not saying this is your problem, just passing on what I went though since your issue sounds exactly like mine was.

 

[Russ B]

Change the distributor. Cheap fix. Distributors are notorious for internal corrosion due to lack of ventilation. Check for excessive rotor movement.

Did you check base timing with distributor wires disconnected?

Might want to check engine compression.