have a 1996 gmc yukon with the 5.7, normal driving and startup it does fine and when in park there is no issue but when in drive right at 2k rpm's it acts like it has no power and then around 4k it starts clearing up, has new injectors, fuel rail, fuel filter, cap,rotor, plugs and wires and the SES light came on a few weeks ago saying the bank 2 cat was bad, so i had it replaced and it hasnt been on since. anyone have any idea what the problem might be??