Yesterday my firebird set a code 36. it was hard to start cold, then ran fine to work. left work and same thing. like to never got it cranked. this time it skipped and sputtered all the way home. took it out again after cool down. ran fine with no codes. this morning it was hard to crank again so i drove the tahoe. this opti is less than a year old. it is an AC delco with less than 2,000 miles. could it be the coil going bad? i haven't had time to check the wiring harness yet. i hate this opti-spark ignition.

 

It is your opti. Sorry. I had mine go bad in 36 miles (bad bearing) and then in 1550 miles (code 36) so it is possible. While you have it out, check the wiring just to be sure. Mine was exposing wiring from insulation cracking with age. Better yet, just replace the opti cable while you do the rest.

Please note that the only part that is probably bad is the optical encoder. This little gem is 1" X 1" and is easily replaced (once the opti is out) however I have not found a source for only this component. Checker has the rotating side available (with core) for about $140 or so. This is the side that goes bad.