Problem with 1998 Pontiac Grand Prix GTP

[GoBlueDawson]

When I'm driving the car under 3500 RPM it drives perfectly fine and starts right up but when I try to get on it a little bit at 4000 RPM it starts missing and will sometimes throw the cylinder 6 misfire code. I've replaced the Spark Plugs and Wires and am still having the same issues. Any help would be greatly appreciated, I miss going fast.

 

[BillBoost37]

Did you have any issue one day that led to this?

 

[asite57]

i would move the #6 coil pack around to see if it follows it, that would tell you if its that. if you have the tools i would check what each cylinders fuel pressure is, if you wanted to take more of a shot in the dark you could just run sea foam through your engine to clean the fuel system.

also im assuming that your maintenance is all up to date, that means new:
plugs
wires
fuel filter
clean maf

if you havent done those things do them first

 

[Scottydoggs]

how many miles? clogged cat maybe?

 

[GoBlueDawson]

Finally have a computer so I can respond for once to my own thread, I ran sea foam thru it and no difference. It hasn't gotten any better or worse. I don't know of a way to check my cylinder pressures but I will move my coil packs around and see if it travels. May be a stupid question but where is the MAF sensor and how do I clean it? I'm assuming the throttle body.

 

[GoBlueDawson]

126k miles and i dont think its a clogged cat due to no odd smell

 

[Fivefingerdeathpunch]

Take it out and clean with MAF sensor cleaner.

 

[GoBlueDawson]

Alright I'm down to what I think are my last 2 options its either a faulty injector so I'm gonna try to switch them around or a chipped Piston which I think is highly unlikely considering this car has never even been past 5500 RPM (Grandpa ordered new from factory in 1997)