i have a 90 s10 blazer with a 4.3 vortec and i just replased all of my spark plugs and wires but i got the wires mixed up and tried to put them all back on and tried to crank it. it backfired really bad and a loud knockin but i think i put them back corectly now by the firing order and i gaped the sparkplugs at .35 but it runs great while driving but at idle it misses and stalls so if yall can help that would be great!!!

 

You didnt change the rotor button and cap too? How come, those are the cheapest of the ignition parts.

Look aroound here with the SEARCH function for the firing order. Or here it is.

 

Look for a vaccumn leak. At idle is when it will make the most vaccumn.
good luck, webble

 

Replace the cap and rotor. ~$25 and 20 minutes of work. Might as well take the EGR off and clean out the valve with some throttle body cleaner (be careful not to get it on the diaphragm!) while you're at it, as that might be a slight vacuum leak. Pipe cleaners work well for getting carbon deposits out of the passages too.

 

My 94 blazer idled really bad but run out good and it turned out to be the spider injector assembly leaking. Hope that may help some.