K, question about this notorious code. My brother gave me his truck to drive and diagnose and fix it for him because emission testing is coming up.

2 years ago he replaced the intake gasket and all plugs and wires. the code still did not go away but he has been driving it ever since because the truck runs good even known the SES light is on.

It has a slight mis at idle but runs good and cant feel a miss under load.

I have a tech II and have been trying to figure it out with no results.

Fuel pressure is good. 60 with KOER, drops to 48 or so with Key off.

Vaccum is around 21in at idle and fluctuates with down to 18in. when the miss is felt.

MAF is around 4.8 - 5.4 g/s at idle.

o2's are all reading good, fuel trim is good.

ONE THING THAT SURPRISED ME is that when the MAF sensor is unplugged the misfires go away?????? I've been reading it could be a million different things.. what does this leave me with?

he replaced the intake gasket 2 years ago which didnt resolve the problem and i just recently sprayed carb cleaner all around the intake and checked hoses but no change in idle or nothing found where I could have a leak??? help pls..

 

Was the air intake altered?

 

No cai, stock motor, everything in stock form, 2001 tahoe,