My current temporary winter beater is a 1994 Saturn SL1 5 speed with the sohc engine. It's got 195k on it, and I've (within the last 500 miles) replaced the plugs, wires, both coils, ignition module, fuel injector, oxygen sensor, valve cover gasket, battery, all engine mounts, and a new OE muffler. When I first get in this beast after it's sat for a while in the cold, it bucks hard from off-idle to about 3,000 RPM. It's worse under load, especially around 2500 RPM. It does get better the warmer the car gets, but never completely goes away. I've got no idea what this might be. It doesn't throw any codes, and the problem's the same after seafoaming, running Lucas fuel treatment, and chopping the cat. The only thing I haven't addressed yet that I know has an issue is the little hose that goes between the valve cover breather tube and air box has a crack in it and is leaking oil, but the car doesn't have a MAF, so I figured it shouldn't affect how it runs. Anyone have any ideas? This is one particularly annoying issue, as it REALLY hurts physically to drive it like this. Like someone learning how to drive a stick on a crappy rollercoaster with touchy brakes.
