ran fine no problems 100000 miles dont touck anything turn key starts up,changed spark plug (new style gm gapped .040) and gm wires.now cranks over wont start,step on gas some will start up with gas smell then runs fine after starts have 1000 miles runs great, next time cold start same thing,wonce starts runs great.Put old spark plugs that I changed at 100000 miles gapped .060 + most around .090 turn key fires right up. Any ideas !!!

 

Sound like you have the wrong plugs and/or plug gap.

Go with the OEM plugs originally equipped with your truck and the plug gap.

 

X2. .040" sounds like a gap for a point distributor. There should be a maintenance sticker under the hood with point gap that engine should be.

 

The wires are ac/delco factory wires and the ac/delco spark plugs that came in it are no longer available and a GM service bulletin says to use the ac/delco Iridium Plugs gapped at .040 as they come pre-gapped to .040 which they are. Thanks