the car runs great till it gets warm...then it starts hesitating and sputtering, a really rough idle and looks to be running rich(judging by the black smoke coming from the rear). a nasty loss in power. then the SES light pops on and everything smooths out and the car runs great. then the the light turns off and its back to running like poo. i put new o2s in and MAP sensor. the pcv valve is still good and has good vaccum.

ps this started around the same time my rear main seal blew. im leaking oil like a mf. when i changed the o2s it seemed to run fine for about a day. possibly luck. could the oil be screwin with the o2 sensors?

 

rais ur hand if you think it could the knock sensor! just an idea.

 

Same problem here.Changed all seals, new O2 and having the same exact problem.