Had an issue that my jeep starts and idles smooth but when trying to give it gas it barely has power and the RPMs will fluctuates from 1k-1.5k and just doesn't want to go anywhere. My initial thought since it was idling fine that it had to do with the TPS sensor. Since it is only $35 I bought a new one and replaced. Starting it now it barely idled and was terrible. Tried resetting the computer by removing positive battery terminal for a few minutes. Started again with the same crappy idle. Figured to try and install the old TPS and now it idles crappy with it.

The CPS, Cap and Rotor were replaced last week. I feel it isn't fuel/ignition issues since it was starting and idling fine. I believe it to be electrical since it is when I go to give it gas that issues occurred.

Any other thoughts?

 

You getting check engine lights? If so a code reader will tell you what is showing trouble. Some stores will read the codes for free. I would check before throwing in more parts.

 

No CEL at all. Even after changing the TPS and it was running bad, it did not throw anything.

 

Check the fuel pressure.

 

How is the IAC?

 

Sorry, but whats an IAC?
Thanks!

 

Idler Air Control. It controls the amount of air going into the engine and the computer matches the fuel input.

 

IAC was cleaned week before last. Should be fine given it was idling great.

 

Back to the post above then, did you check fuel pressure at the rail. You can put a gauge on the end. What year is your Cherokee?

 

No I haven't but wouldn't fuel be fine since it idled fine? It shows it gets fuel to run.

 

No, it could be lack of pressure. Giving enough to idle but running rough when you press the gas pedal. There is a check fitting at the end of the rail and depending on the year the pressure is either 39 or 49 psi.

 

Just because it idles fine does not mean you have good fuel pressure. You may have enough fuel to idle with NO LOAD on the engine, but not enough fuel when there is a load, such as trying to accelerate. Check the fuel pressure with a load on the engine with a proper gauge.

 

This^^.

 

Im having similar issues currently. Only mine only does it when cold. Once warm runs fine. 96 4.0. Id start with the pressure. Just cause it runs doesn't mean its getting the proper amount of fuel.

 

It is a 1996. I threw a gauge on it. First time turning to On position it only came to 25 PSI. Second time it primed to 49 PSI. tried starting and idled rough bouncing from 30 - 49 PSI. Knowing that it doesn't have enough, what should I look at next?