I have a 2000 Chevy Blazer 2wd with the 4.3. I have a problem when I accelerate hard to get on highway. Seems once I go over 3000rpm the engine feels like its running on fewer cylinders. I have had a few old cars and it kind of feels like a floating valve. I turned it up with a new aftermarket upgrades.Yes i have rechecked everything I have don to this point. I've also installed a flowmaster muffler and a k&n air filter. I have scanned it and I get a coil misfire code but I'm not to sure about that. Seems it should run bad under any acceleration if that was the case. Idles fine and starts right up. I've also replaced the fuel filter about a month ago. Anybody ave any ideas?

 

Coil for sure-even new wires and plugs-Use dialectric grease!Also consider a new module although it seems the mod is working fine from your symptom description!
I don't think your coil is good-as the rpms increase-so must the voltage!

 

Well last night I cleaned the throttle body and put Lucas fuel injector cleaner in the fuel tank. Didn't really do to much to fix my problem. Runs better but still has the same issue. I guess I will put the coil on tomorrow and see what happens. (yes i know it might take awhile for the fuel injector cleaner to help if at all)

 

Changed coil and still no change. Guess maybe intake leak? Guess nobody else has any ideas. Throttle body and Mass air flow sensor have both been cleaned also.

 

Still having the same problem. Replaced upper plenum gasket. Checked for leaking fuel lines while I had it off. Didn't find any. Also took apart purge sensor and cleaned it. No change. I also noticed that it kind of runs ****ty if you run to the gas station. Shut if off run in and out real quick. When you start it back up it runs ****ty for a minute or two till it seems to clear its self out. Yes Ive given it a full tune up and changed fuel filter.

 

Does the check engine light flash or remain on while driving? Have you checked fuel pressure and leakdown? These things are real fussy when it comes to ignition parts, especially plugs, cap & rotor. Anything other than AC Delco, you're asking for trouble. What diagnostic trouble codes were retrieved?