I have a 93 240sx s13 5 speed. Have a KA24de that seems to want to be naughty lately. I had a problem before where it was runnin bad so i changed the #1 injector and it ran fine. Got a cat less than a month ago and installed it. Got home the other night ( a few days after I changed the injector) and it was running like poop again. we had checked the plugs, wires and compression test and everything checked out BEFORE I got the injector. Now i get home and look under the car and the back of the < month old cat is glowing red!! I take it back and was told that it came apart inside, got another and just put it on... STILL runs like poop. injectors- ok, plugs/wires-ok, cylinders- ok. When i drive down the road it backfires really bad. My GF stood outside and i drove pasts her and she said when it was backfiring that it was shooting flames . when im going down a hill and stay off the gas in about 2nd and just let it cruise, i can barely put my foot on the gas and it sounds like a gunshot. When i dont have my foot on the gas it has a rhythmic popping sound.. My GF's brother says that i might have a valve that is sticking? I have tried nearly everything.
OH, and checked the MAF, and its fine too.. Sucks ass, this is the first time in over a year that it has really messed up.