KA24E WOT Problems

[unityGRSRTS]

Ok, so i finally got a 240. 1989 KA24E w/ 60k miles!!!Anywho, after taking it into a shop to have it looked at. This was the list they came up with: All new belts, Tires, Exhaust, Small leak in valve cover gasket, rear calipers, front pads. Now when i got the car and test drove it, when i gave it WOT it got to about 4200k rpms n the exhaust started to sound like in was backfiring...or sputtering. And it kind of had trouble accelerating. Its really hard to describe the sound. But this has really made the car slow. Now since they didnt mention anything about it, i dont know if they didnt notice or if its just related to one of the repairs.(mind you i only got a quote on the repairs) My question is if anyone knows what this could possibly be. Im wondering if it has something to do with the exhaust since its full of holes. Or possibly something w/ the cat and O2 sensor. Im stumped. Any help would be appreciated.

Andrew

btw, its not the fuel filter because i changed that already so no dice.

[180fan]

I used to get weird popping sounds when my AIV was stuck open. Another possibility is that you're running way rich, try cleaning the MAFS and also check your TPS along with your CTS. Your O2 sensor you should replace anyway since it's part of having better mileage and more power aka a tune up. Do it. The holes in the exhaust I don't recall making your car make popping sounds. It'll make your car run a bit louder if I recall correctly at one of my buddies cars. lol. Run those checks first and post back.