Well, i jsut got the 89 iroc about 2 weeks ago. THe trans is a 700r-4 with a transgo, vette servo, and 240-2600 stall. Well when i hammer it once in a while the rps will shoot up to almost 6k and shift real hard(sidways chirp). Im not sure if this is a slip or what but the id i bought it off of said its shifted liek that since he had bought it. Can i fix this to shift around like 5200.

 

Try adjusting the throtle valve cable for the transmission.