i have a 98 blazer which i bought with a missfire on cylinder 1 and 2, it runs like crap at low rpm but after 2000 or so runs absolutely beaufitully, i started by cheching compression and it is in spec, put the spider in, new plugs, wires and distributor, new timing chain anc cover, checked fuel pressure at the tank and changed the filter, i am completely lost we even took the rocker covers off to see if possibly the lifters werent moving at low rpm now i am completly stumped, could this be a plugged cat? please help!!!

 

Have you cleaned the EGR valve and the MAF sensor? What brand did you use for the tune up? Does the cat rattle or smell like rotten eggs in the exhaust?

 

i havent looked at the egr valve yet but the Maf looked fine when i looked at it, and it still misfires on those two cylinders, if it was the maf itd probably throw a maf code, and no the exhaust doesnt smell just burns very hot

 

MAF doesn't always throw a code, mine was pretty dirty and I never had a CEL. If it were me I"d go ahead and take it off and clean it with some CRC MAF cleaner and see if that helps, it couldn't hurt anyway.

 

Try pushing down on the spider wire harness cap and see if it stops misfiring. Dont push down hard just push on it while its idling. Sometimes the connections wear out and pushing on it will reconnect it. Happened to my 2001 blazer.

 

what was ur fuel pressure, u need to do a fuel leak down test.

 

Did you replace the connectors?