[91Caprice9c1]

You can check the Diatnostic Trouble Code (Check Engine Light) yourself. Have a peek under the driver side dash at the fuse panel. You will notice that one of the slots is raised off the panel a bit - it has some built up plastic around it - located toward the firewall on the panel if I remember correct. Stick a fuse in raised fuse holder, sit in the driver seat, turn the ignition on and count the CEL flashes.

Blink-pause-Blink-Blink = 12
Blink-Blink-pause-Blink = 21

Blink-pause-Blink-Blink--long pause--Blink-Blink-pause-Blink = 12 and 21

When all the DTC's have been displayed it will repeat them.

Have you checked ignition timing?
It may be possible the guy R&Ring your timing belt got it off a little.
Have you checked fuel pressure?
Everything plugged in under the hood?

-MechanicMatt