I bought a 1993 SC300 with the stock engine in it with ~120k miles on it, car is totally stock. After a few thousand miles and a few baseline dyno pulls (they were free, I figured "what the heck" ) it started surging at idle, was down on power, and generally felt crappy. I drove it like that for a few days, uncertain of what it was (since I had just bought it and wasn't sure about its maintenance history). Driving it one day, it felt sluggish and unresponsive and started smoking big plumes of whitish smoke out the tailpipes, so I figured the engine was toast. I had a compression check done, and the results were crappy for cylinder 2 (120).

I bought a supra TT shortblock, thinking I'd throw that in there and begin the money wasting, but didn't get around to it for a few weeks. Three weeks later (aka, today) I started the car and it started and ran fine. No smoke, no oil consumption, good power, good responsiveness, no lumpy idle or anything. My biggest complaint right now is that it misfires every once in a while at idle, making a little pop pop sound out of the exhaust, but I attribute that to some bad/old gas in the car.

So here's my question: What would cause a car to "seem" like it had a blown engine, then get better after sitting for a few weeks? I'll report back if it starts smoking again any time soon, but I just thought I'd ask here first for ideas. I checked the coolant, it looks clean and clear, so I sort of ruled out BHG, but that's still a possibility in all honesty.....opinions?

~Tim