i get horrible gas mileage. 11mpg. The car started with just a small hesitation while stopped in drive. The rpms drop about 400 rpms with this hesitation. It became more frequent...and then it became constant almost like a bucking motion when accelerating. I have replace the fuel filter. It isn't a missfire. I've tested and replaced all ignition parts. THe car after sitting will run fine for about .5 miles and then it starts again. Also the car when cold very cold will start fine. If it is warm or has been ran within the last hour it has a hard time starting. I've followed the haynes manual instructions for timing and have replaced the timing belt as well as installed and timed it 4 times. The tick marks on the belt never realign. But if it was timing the car wouldn't have ran smoothly for 1000 miles after being timed right....>


I dunno what to do or where to start... fuel pressure regulator? maybe does that sound right? SOME ONE HELP PLEASE

 

Start by looking for vacuum leaks, thats the most likely problem. Vacuum hose came off or leaking, or intake manifold gasket cracked which is fairly common on '98+ rodeos.

Bad o2 sensors could also cause it. Would make it run very rich. They can start reading wrong just enough to cause problems without setting a CEL code.

 

I agree,check those out. If it runs smooth at cold start it may very well be a bad O2 sensor. The cars computer changes the fuel to oxegen mix when starting cold, and adjusts it as it warms. You say you checked your plugs? What was their condition? Were they fouled? A lot of soot? Oily? Gaps? Edited by: Keefbikes

 

i had the same problem. Someone told me to check my spark plug gaps they were at .050 and i changed them to .035 and now it runs pretty good the bucking stoped so far. but I want to put it on a highway for the true test

 

i would say o2 sensors, i had the same problems on my 96