Hi Iam running a 700r4 87 iroc today I took it out an it shifts fast threw the gears its like 123 in no time does someone know what could be the problem?

 

I'm no expert , but , if it were mine I'd be making sure the transmission's Throttle Position Cable is still attached properly to the throttle linkage .

Lots of folks mistake this for "Isn't it just a kickdown cable" and NO , it's far more than just in control of passing gear kickdowns , it controls shift points in relation to throttle position . If the plastic attachment is broken and the cable is not moving with the throttle , it will go through the gears as though your barely stepping on the gas even when your much further into the gas pedal . This is known to fry these transmissions since it ALSO controls "line pressure" and the clutches are not as firmly engaged at the lower pressure resultant from a broken/improperly adjusted cable .

Good Luck with it ....