i have a misfire cylinder number 3 and 5 misfire is so soft at start up you cant tell its there. drive for a little while and come to a stop at a light stop sign or what have you and its bad enough to tell put it in neutral and rev the motor up and then put back in drive and the misfire goes away.have had the heads redone new coil packs new plugs and wires. please help have about had it with this truck.

What are the trims doing? Injectors OK?

What carfixer007 said ^^^^^^^

. . . and:

How many miles on it?

How many miles have you owned it?

What is the fuel pressure at idle?

Why do you think this is related to AFM?

there are 273k on the vehicle rebuilt motor 6 months ago. Had to have the heads redone 3 months ago due to blown head gasket my fault. Was only using the arm as a forum. I don't know the fuel pressure at idle. I have owned this vehicle for 4 years now. Biggest thing is once misfires at the light and I put it in neutral and then give it gas the misfire goes away

IMO, if it was a fuel delivery issue, I would think a P0300 would be in order and not limited to one or two cylinders.

Swap the injectors with 2 and 4 to see if the issue follows.

Can do a "Crankshaft variation learn" procedure with a scan tool and see if that helps.