Im working on an 03 Impala, 3.8L. The MAF sensor was bad so I replaced it. Everything was fine for about 10 miles. Now the engine bogs down at 3000 rpm and doesnt shift right. Unplugging the MAF helps a little but still runs pretty poor. Its not giving any codes, air filter is good and fuel pressure good. Anyone have any ideas?

Thanks

 

Could be a bad new part. I have seen the MAF sensor pigtail go bad many times. Try wiggling the wires going into MAF see if it change the way it idles. If wiggling the wire makes the idle change at all replace the pig tail.