4.3 engine misfires early as if moisture is problem

you may have an inj spider issue. these were covered under warranty for 10yrs 100k miles extended warranty by gm. i rec you seek a diag and est to determine if your spider is going bad.you can ck this run veh for a short period o f time while its runing bad shut it off and on top of intake manifold there is a blk 2 " plug on top remove plug and look to see if the intake is filling with fuel.if so its a good indication that its going bad

had that problem with my 98 4.3 and it was the crank case vent under the distributer plugged up and the mass air flow was dirty