have a 94 k1500 5.7 with ignition problems. It skips at idle the tach started jumping around only on idle and when you put it under a load like keeping speed on the interstate the valves start rattling after a few minutes them cylinders start misfiring then the ignition cuts in and off but if you coast it it’s comes back around. New plugs wires new distributor new coil . I don’t know what else to do here can someone please help me as I’m about to just put a hei distributor in it

 

Might need to pull the valve covers off and adjust your valve rockers. It's not a new Chevy pickup anymore. It's 28 years old.

 

I can I would think if it’s a valve issue it would change in someway as it warms up. It’s something electrical. The valves are not gonna make the tac jump around. Starting to show signs it’s the pcm going bad because when you unplug the wire for the ignition to the pcm it stops skipping as bad. But at this point I’ll check the valves preload and adjustment. Also if it was the valves it would slowly get worse this problem just started one day and hasn’t stopped