Ok, this is some wierd $#!t here. When I'm driving in low RPM's I don't seem to have a problem. As soon as I get WOT and start reaching my high RPM band (5000 or so) the engine starts to sputter a little and the Tach jumps up and down!!! I thought it might have been a bad battery connection but I replaced the battery and the terminals!! So what the hell is going on??

Could it be fuel related?? ie: Fuel Pump, injectors, or filter

 

It could be misfiring....bad gas....throw some High Octane shit in there and then throw in some injector cleaner and see how it does

 

How many miles on the car? Auto or manual? Need more info than what you provided so far.

 

It has about 150k on it!! Automatic transmission too.