need help whith 99 mach z not getting any to end rpm or speed starts fine goes great out of the hole tacks right to 8300 then falls off and stayes at 7300 rpm you can give it throttle and no change at all any help would be great thanks

Could be a number of things. Check for exhaust leaks or carb problems. After that do a compression test...

Sounds like a weak secondary spring possibly. A weak spring would cause the driven clutch to open alot sooner than it should be, therefore engaging a higher gear ratio too quick.