misfire 2 4 6 cylinders

i have a 2001 silverado 4.3. the other day the service engine light came on and the valves were pinging as i was going up a slight incline and the truck was shuttering, then the service light started blinking. my buddy put his snapon scanner on and the first on the list was the MAP sensor along with some other minor problems. i changed the MAP sensor and still have the same problem. cylinders 2 4 and 6 are firing intermittintly. so far i have checked the plugs, wires, swaped out the coil, and the ignition modual.
 today i am going to check the crank sensor and the distributor.


  For your information this engine only has one fuel injector


thanks for any input

joe  

is there a chance that the fuel pressure regulator on the fuel injector body went bad... it happens a lot on vortec motor...    leaking fuel only goes to one side of the motor..

dorman has the replacement fuel pressure regulator as an individual part.. motormite #55162

you will find that one side of the intake runners is really clean when these go bad...  

checked fuel pressure and it is good

thanks  

Sounds like an ignition/timing problem. I'd pull the ignition module and have it tested at Autozone to see if it's bad.

From there, it could be a bad crank sensor, though I can't remember if the 2001 4.3Ls still had a distributor or not. All the V-8s were distributorless, but since the old 4.3 V-6 is based off the Gen I small block, it could still have a distributor.