I have a 93 zj V8 150k miles, when I go to start it after it's been sitting for a couple hours it has a hard time staying running. It will idle real rough and idle lower and lower until it dies. I have to keep tryin to start it for about 5-7 minutes before it starts up good. It runs great no codes and no stalling. Any ideas? Oh and it will start right up if I have been driving for a while before I shut it off

 

Bump??

 

sounds like a minimum idle air flow problem.

Clean the throttle body with carb cleaner, carefully remove the Idle Air Control valve "IAC" from the throttle body and clean it with carb cleaner and make sure you clean out the passages in the throttle body were it mounts. Be careful not to damage the "o" ring when you put the IAC back in. When you are done you will need to reset the IAC values stored in the PCM. Remove the negative and positive battery terminals from the battery and touch them together to clear the "KAM" keep alive memory in the PCM. Reconnect the terminals and start the engine, let it idle for at least 5 minutes before giving it any throttle , then take it for a spin around the block. Should be good after that, it not, replace the IAC and clear the memory again.

 

Did that already a couple weeks ago when the problem started,any other ideas?

 

you already replaced the IAC???

 

Yes and cleaned out the throttle body. I know my TPS is bad but I doubt that's causing this. I am leaning towards my crank position sensor, also I have fuel pressure, spark and air.

 

Check the hard plastic line that goes from the intake manifold to the MAP sensor for cracks. Mine started running a little funky until I found that vacuum line cracked. Fixed it with a piece of vacuum hose and now it runs great.

 

I already checked that line and all the other vacuum hoses, its not a vacuum leak- I can smell gas bad when I'm cranking it and its tryin to start. There is no leaks so its the exhaust, any ideas? Thanks again for the help guys!

 

It also so won't take off as fast, it doesn't bog down it just acts like it is missing or something

 

Have you tried doing a compression check?

 

Also what kind of plugs do you have in it? Back when I didn't know any better I thought I was doing a good thing by getting those useless Bosch 4+ platinum plugs. They did more harm then good to my performance.

 

I put autozone platinum plugs in abouy 2 weeks ago, gapped them to .035 , problem started before that tho

 

I have not done a compression check yet,today I am gonna get a new distributor and CPS hopefully its one of those. You can smell gas from the exhaust bad,so I think it won't stay sparking so its not completely burning the fuel

 

Coil.

 

Ya think so? Ill grab one of those to,I don't wannabe be throwing money at it tho so what 2 should I get first?