rpms fluctuating

[Shawn3]

Hi. For 8 months now I have had a problem with a 92 Jeep Cherokee. When I start it up the rpms will flucuate between 2000 and 3000. If I try and drive it, it jerks and won't let me go above 40km/hr. Iv'e changed the TPS, the fuel filter, checked for vaccum leaks, replace rotor and cap and wiring, also cleaned the throttle body several times. It;s now getting worse and worse. When I use to step on the gas until it reached about 4500 rpms and hold it there for a min it use to go away and work fine. Now that does'nt even do it. Please help. I've just about had it with this jeep.

[nitrotechnician]

I had a similiar problem with another vehicle. It turned out to be a bad fuel pump. Sitting at idle, the fuel pressure would be okay so I didn't think it was fuel related. As the pump slowly got worse, so did the symptoms until the pump finally went. If you haven't already, check the fuel pressure and make sure your fuel lines aren't blocked. If your sure you got proper spark then checking the fuel delivery is the next step. I got a lot of help from this site when I was having issues and that was the first thing they told me to do. Hope that helps.