My car went into limp mode and threw a p0101 for a bad Maf sensor, so I replaced it. All the power is back and the cel didn’t come back on. But now my throttle lags when revving it up to get in gear. Also when downshifting and decl the car is back firing way more then it used too. There are no codes for this problem. Bad fuel filter maybe? Going to try a throttle relearn.

2009 Chevy Cobalt SS/TC no tune.

 

That code usually means you have a boost leak. So you probably replaced the maf for nothing.

 

Yes but the cel has not came back yet after 4+ hours of driving and I make complete boost.
also A/F are fine

 

Step 1 for P0101 is always boost leak test. Even if it doesnt seem like its leaking it could be.

Very low chance, but you couldve had a leak at the MAF itself that was fixed when you replaced it.

 

If you have a boost leak then your wastegate shuts more than usual trying to achieve your target boost by spinning your turbo faster to compensate for the lost flow, so it's possible with a small leak you wouldn't notice lowered boost pressure; but I'd expect the ECU should pick up on this and throw another code eventually so keep your eyes open.

Before continuing to run the engine, you should do a focused once-over of the boost tract and look for weird stuff like melted, cracked, or loose things.