I have a 92 and when I crank mine the temp gauge pegs and then drops to where it should be. what is wrong with your tach?.. More than likely your sending unit is bad, stuck on 1/2 tank

 

I know, wont happen agian (thats y I said sorry for interupting).
As for the tach, I believe the buffer is bad because I had the ADLD port connected to a Snap On computer and it read 1,000 rpms while the IROC's tach said 3,300. The temp sender wire was cut by the PO. So little by little im restoring my Camaro. Need to get a temp sender.