Performance Chip installed, Service Engine light wont stop flashing

I just installed a JET stage 1 performance chip into my 1990 K2500 truck. The instructions said to remove stock chip and install new chip. Pretty straight forward I thought. As soon as I turn the key the SES light flashes like a strobe light. I took it for a drive to see if it would clear itself, but the entire time the light stayed on. I shut the truck off and turned the key on again and the light still comes on and flashed. The truck seemed to run fine. I have no Idea what is wrong with it. Could it be possible my computer is on the fritz? Any help is appreciated.

Well, given that it started doing this immediately after installing that chip, I would think the chip is the problem. Put your original one back in and see what happens. If the manufacturer stated that premium fuel must be used, do that. Check codes if you didn't already.