Installed a new used cluster, swapped out the speedometer box with old so the miles would be accurate, however, the speedometer does not work correctly now.. inaccurate readings and fails to go back down. Suggestions?

 

sorry... 88 4runner.

 

OK... You've got an '88 4R. What was it that the new cluster came out of?

If it were a later (electronic) speedo, I'd start by guessing your replacement came from a vehicle with a different # of cylinders. Since the '88 is mechanical, I'm guessing either a messed-up cable linkage or damage to the new cluster???... If the 'new' cluster is for a different application, maybe your swapped (original) speedo unit doesn't work with it?....