95 blazer new pump plugs wires compression all within spec as well as fuel pressure replaced spider injection it was leaking like a mother in the intake. Tps and egr replaced as well. The problem has stayed the same after all this with the problem being multi missfire at idle and on first start up loped idle and driving down the road is impossiable. It never dies drinks gas but when you get about a quarter mile down the road it runs 90% better but not as much power as I believe it should. The check engine was around the egr. Weird thing is unless you drive it the check engine stays off once you finally make it down the road it just takes off like a bat outta hell and the check engine comes on. Any ideas? Driving my mad.