I have a 88 5.7 IROC. The previous owner installed a 1989 or later tpi manifold without the ninth injector. The car is very hard to start when engine is cold. I have replaced injectors, manifold temp switch, checked fuel pressure( it is within specs). The only thing left is computer or prom. The info I have found on the Ecm's, the part numbers are the same for 88 and 89. That leaves the prom. Will the prom chip change the cold start enrichment so the engine will start or do I need to look some where else?

Absolutely, the prom change will fix this issue. The '89 proms have the cold start deleted in favor of enrichment for a cold start.

You'll need to have VATs deleted if using the '89 PROM, easiest way might be to see if TunedPerformance(here on TGO) is still around, or maybe Ed Wright might still be doing chips.

Thank ya'll for the info. Now I have something to go on.