I can add that I am not sure about the 580 EFI, but the wife's 98 ZR6 EFI, you can't buy the TPS, it only comes with the throttle bodies. It is very finicky. If it's not set perfect the sled will backfire and miss...very nasty!
Likely your problem is not the TPS, however it may simply be out of adjustment! But I don't know much about the older sleds EFI....