94 xlt chugging while idling!!

[purple-x]

i finally got my x to run as well as it can with 180,000 miles on it and now this. when im driving down the road its fine other than the poor fuel mileage but when i stop at a light the rpms slowly drop down to 500 and then it starts to chug a lil then it gets worse. it gets to the point where the whole car is rocking forwards and backwards slightly. i though maybe it was the torque converter so i put it in neutral and it still does it. has anyone experienced this before and is there a cheap way to find out what it is or to fix it. . . im a lil strapped for cash.

 

[YourNameHere]

Sounds like a vacuum leak.

 

[purple-x]

i have searched as many of the vacuum lines as i can find and found no leaks im almost thinking it may be the maf sensore or the idle air control valve. but im not sure and i dont have a parts truck to throw parts on it and those two parts are pretty expensive and i have tried cleaning both and it didnt work

 

[marragtop]

COuld be the IAC, or fuel filter. Probably wouldn't hurt to throw some plugs and wires on it.

 

[Maniak]

Check the fuel pressure. After I rebuilt my motor I had a similar symptom.

The truck would start and all seemed fine.. I would drive to work (30 miles.. mostly freeway). When I got off the freeway the RPMs were low and the truck was running really rough.

When troubleshooting it I noticed that it made a black spot on the ground at the exhaust. I figured it was running rich so I checked the fuel pressure. I had between 60psi and 90psi at idle when it had the problem. What was wierd was I didn't have really high fuel pressure when the truck was first started in the morning. Only after driving it a bit.

I installed a new Fuel pressure regulator and all is fine now.

~Mark

 

[lmatt]

Could also be the affect of ethanol fuel. My 91 will NOT run with the 10% blened fuel. I have started running BP's gold 92. Get GREAT fuel mileage, and has 250,000 miles on it. No pinging. No problems. I have proven this is the problem. Had ethanol in it, acted up. Put non-ethanol blened fuel in, no problem. And yes, majority of the stations all have the 10% blened unleaded now. Your hard pressed to find any regular non ethanol gas.

 

[purple-x]

i have done a complete tune up on it. . . plugs, wires, fuel filter, i replaced the dpfe sensor(which helped my cel), pcv valve, and i went to an auto shop and he had a couple junk explorers and i swapped out the maf sensor, idle air control valve, and tps. i checked the fuel pressure and at idle i have 35 psi. when i rev it it goes to 42. still having this problem. i called a local 4x4 shop and he said these have a problem with the heads cracking between the valves, would this happening cause the problem. it has 176,000 on it.