2001 chevy 2500 6.0 rough running and no power on acceleration

[ian h]

 i just got a 2001 chevy 2500 hd and im having issues getting it to run right 

it has a new fuel filter 

new fuel pump

new plugs

new injecters

whole fuel systems been gone through and i got the codes for maf, misfire on 7 and 8, 02 sensor

i cleaned the maf new plugs and swapped the wires on 7 and 8 and still rough idle and no power in drive when in drive it sounds like a john deere from the 50s

[richard wysong]

Vacuum leak, coils?

[davester]

intake and/or exhaust leaks

useful to check the fuel pressure at the rail anyway, both at idle and at say 3k rpm

[CamGTP]

Possible plugged exhaust too.

[ian h]

On 6/2/2025 at 5:34 PM, CamGTP said:

Possible plugged exhaust too.

no cats or muffler

[MORSNO]

12 hours ago, ian h said:

no cats or muffler

 

It needs backpressure from a muffler, and have you cleaned or replaced the O2 sensor?