4.3 vortec engines

If you done a tune up and the engine still is not running right. Before you go and replace alot of sensors and computers, pull the distributor out and check the drive gear on the bottom. if it worn even a little replace it. alittle wear will cause an engine to shake. i've worked on them were th engine was spittin and sputterin. the gear was chew about half way thru. replaced it and it purred like a kitten. to do the job you need to
1 pull the wires on one side of the cap and mark them
2 pull the cap
3 pay close attension to where the rotor button is pointing, mark the direction if possible
4 remove the 10 mm bolt that holds the distributor in place
5 pull the distrubutor up and out
6 check the gear. if there is no wear replace in reverse order
7 to remove the gear you need a punch pin, knock the shear pin out of the hole pull off gear and replace with new one. replace shear pin.
8 reassemble in reverse order.
good luck