grab a pocket scan tool from parts store and see what you fuel trims look like or have someone who knows how to do that do it. it sounds like your experiencing a lean condition when your trying to accelerate and the popping is more than likely a lean backfiring condition. and since your original codes were rich fuel trim codes, it's very likely your maf sensor is the culprit. cleaning it with maf sensor cleaner would be a start. make sure its unplugged before you do so and dry it out before you reattach it. if that fails, take to a skilled mechanic. do not make the problem worse by throwing random cheap aftermarket parts at it.

 

Yah, the dealership says it was the 02 sensors and I just bought some plan on replacing them next weekend. But now I mean the car wont go above 30 mph, and I think its the cat. I'm just gonna get a new header and replace the 02 sensors and see what happens after that. thanks though.

 

Im glad you made this thread, because Ive been having the same problem on my 2003 GS300 sports design, if that matters. My check engine light and my VSC for the past 2-3 years. My dad has been a Chevrolet mechanic for 30+ years and he has no idea, We brought it to the local Chevy dealer to clean out the fuel system , that didnt work. He finally said to put a new TPS sensor on, and that didnt work, He said that at the dealership they would test bad TPS by taking a plastic screwdriver, and tappping on it while the car is running, and if you hear the engine making noises with small taps, thats your problem. but not mine. Its been such a problem , because either people behind me are thinking im purposely trying to get in a rear end accident, or I dont feel safe pulling out in traffic, thinking my car will hesitate, and get into an accident. It happened one time, and fortunately, a newer Toyota, had to slam on their brakes. It coulda been bad, but I want to know how to fix this problem

 

Like BlackGS said, I changed the Mass Air Flow sensor, but it didnt seem to do the job, however, I tested it out for one day, and I shoulda just kept the new MAF in and see if it would help. My 2003 GS has 130,000 miles on it, and it finally died on me at a stop sign. But it started right back up. Do you have VSC and engine check lights on too ?

 

Im not good at mechanics, and I suck at the terminology, I apologize. Im more auto body than I am mechanics.

 

Mine turned out to be a clogged cat. Thanks everyone that helped.