I drive a 2000 Chevy Blazer, 4.3l, v6, 2wd with 120,000 miles.....when im on the freeway i seem to have trouble getting up to speed, especially going up hills.. sometimes on the freeway my "service engine soon" light will come on flashing indicating a cylinder 4 misfire ( p0304 ) or a random/multiple cylinder misfire ( P0300 )... Usually happens at about 2000-2500 rpms at 65-75 mph...recently changed the spark plugs with AC Delco platinum, changed caps, rotor, and wire sets. Misfire still ocurs occasionally. Any help guys??

 

I don't think anyone is going to touch this one till the moderators scald you and move it to the correct spot! Unless there is some wierd glitch that put this here, try posting in the correct sub-forum for more knowledgeable help.

 

*MOVED*

Clean the EGR valve, double check the connections on the spark plugs and distributor cap (expecially that #4 plug ), change the fuel filter. The wire connectors on the distributor cap can sometimes be tough to get seated properly. If that does not help you may need to have the ignition coil tested.