im almost sure its not the opti, every time i take the car over 5K it breaks up a bit and falls on its face at 6K, could it be that i still have stock injectors? also i have the racetronix fuel system in the car. also when it hits 5K the check guages light flickers on and off, but its like a half assed flicker. im just at a loss because sometimes it does it and sometimes it doesnt. also sometimes the car feels like it drops a cylinder and my wideband goes lean then it will run like that for a bit then pick back up.

 

Whats the fuel pressure doing when this happens? Unless your stock fuel injectors are bad you have no need for bigger ones at this point. Are you getting any codes? What makes you think its not the opti?

 

check to see if your coil is arcing, same thing happened to my buddy

 

If its flicking and the wideband is going lean, if you're speaking of the 97 car in your sig its a random multiple missfire most likely. Smells like opti coil or wires to me. You could scan it and see what the injectors are doing, but that doesnt mean they are all working when you rev it up (they are 11-12 years old ya know have they ever been serviced?). If you're running much higher fuel pressure than stock sometimes this can shut off the stock injectors at high rpm when the coil inside the injector heats up.

 

Check you maf, I had the same thing happen on my old SS turned out to be a bad MAF.