Is anyone on here live I can consult with???

 

I know more about the car than about the computer. (but not much) Sorry if I get this in the wrong place. My car is running exactly like an old carburator set a little lean.. It runs fine for an indeterminate time, then bucks a bit like it leaned out, then picks up and runs fine for a bit. Maybe a few miles, maybe just part of a mile. There are no codes after I reset it. My first attempt read codes-- bad rear O2 sensor and small leak on evap system. I have changed the O2 sensor, run a bottle of cleaner through gas, changed the Gas filter, cleaned the air cleaner with compressed air. all with no measurable change in the problem,

 

Unfortunately I'm not that familiar with carb set ups.
do you remember what the exact codes were? Kinda wondering if maybe the cat is clogged.
If I remember right, the intake mani gaskets leaking caused weird things on the s cars, too. Been a while, as I am an Ion guy

 

Thanks for the reply. (not sure if I'm doing this right..) Codes were PO137 (HO2S circuit low voltage bank 1 sensor 2) PO 301 (Cylinder 1 misfire Detected) and PO 442 (Evaporative emission system small leak detected) I changed plugs and changed the downstream O2 sensor. Reset the codes. Nothing 'coded' in 20 miles, but the running was the same.

 

The cylinder 1 misfire is probably why it's running rough. And can be caused my a vacuum leak. Check the wires to make sure they're not leaking spark. And check the intake hoses and manifold for a leak. Also check the distributor for damage. I've seen small cracks on other platforms cause that

 

Manufacturing issue on 3rd generation SOHC engines. Intake manifold gasket is not supported well enough at installation at the factory. Part of the gasket around the number one cylinder port tends to get sucked in, causing a vacuum leak. Vacuum leak equals lean. The car's pretty old so yours may have just started flapping around so to speak. I definitely agree that is the source of the misfire.

Fix that first, and see how it runs. You should also be able to loan a tool for a back pressure sensor at AutoZone or similar. You remove the front O2 sensor and screw in the back pressure tester. If your cat is clogged and there are no leaks in the downpipe leading to it, you should see an abnormally high pressure. The rear O2 sensor is just a policeman for emissions. It tends to get coated in crap. Especially if your car is burning oil cuz burning in the cat. Obviously the heater circuit went bad see you had to replace it.