Okay. I have a '98 Pontiac Sunfire. 2.2L 5 speed, 174k miles. Starts on the 1st attempt, one turn of the engine and immediately starts missing. I have changed plugs, wires, ignition coil packs, replaced O2 sensors, rebuilt intake, cleaned choke, ensured vacuum lines are connected, changed fuel filters (external of tank and internal the same), pump pressure is within spec. I have also done the old fashioned spark test (set a hot plug on the frame and watch 'er spark, and all 4 cylinders are sparking quite nicely.) The car will run, but there's no power on the low end (>2500 RPM, which I'm not able to get past til the engine gets warm). Once the engine comes to operating temp (195), and I'm able to FINALLY able to race it to 4,000 RPM, and gently let off the gas, it will sit and rough idle. There's no power on the top end. I can get it to 2nd gear, then it falls flat to its face. I have to quickly shift to first and pray I can get it off the road, the last test drive I attempted. This has drove me nuts long enough, and I'm ready to fix it. What else could be my problem?
