Ok 05 silvy 224 cam pav 600 springs hard end pushrods Lt midpipe. Nelson 93 tune cai Ok guys I cleaned the maf and TB and use new ngk plugs gapped to .060, fuel pressure check it held 60 psi during wot and never dropped . Hasn't thrown any codes or misfires, idles fine and drive perfect but if I get to 4k it start sputtering it's driving me crazy started doing it after I pulled my nx kit off also but fuel Shrader valve don't leak or suck air that's all I touched

 

Factory Spark Plug Spec changed to .040 when they went from factory installed platinum to replacement iridium.

If you have NGK iridium they should be .040

 

There ngk tr55 and the ngk I pulled out were the same gapped at 35 and still didn't change it acts the same

 

.035 is probably about right on that plug.

What about plug wires? ever changed them???

Are you sure there seated all the way on both the coil and the plug???

 

Msd wires and yeah I'm pretty positive it idles fine with no arcing or rough idle spots and drives fine and pulls smooth under regular driving

 

have you checked the plugs since this started happening? sounds like they may be your issue.

you mentioned nitrous... that could have something to do with it too

 

Well my plugs were fine but 3 and 5 were white powder when I change them but I didn't pull the new ones out yet

 

I had a similar issue the first cam swap I did, the plugs were fouled/busted tips... changed to some TR55s and cleared it right up.

 

Could I have a bad coil or clogged injector? And it don't make sense how it won't miss or anything driving till I hit 4k. And in park it will rev up to whatever and be smooth so it's only when the engine has a load on it