95 GMC Suburban backfiring

I have a 95 GMC Suburban 4X with 5.7 liter engine, fuel injected, automatic transmission. It's probably coincidence, but after I changed the starter the "Service engine soon" light was on, and the engine has been cutting out and backfiring.

The small wire to the starter forked off and connected to some device on the bottom of the truck. I have no idea what it is. I pulled the connector off to get the starter out, and put it back when I was done. Whether this is connected with the backfiring problem I do not know.

Back in the old days, I'd have gone for the distrubutor and checked the points and timing. With this GMC, I don't know where to start. Does anybody know what often makes these Suburbans backfire and cut out?

Thanks for any assistance.

And the check engine lite code is?

You have to check with a scanner to get the check engine light code, right?

Yes on a 95 ,most likely obd11 or obd 1.5.

The guy at NAPA told me it was OBD 2. Was he talking through his hat?

No. An obd11 scanner is the only way to read codes.

OBD11, okay.

I found a connector that was not properly seated, and connecting it properly caused the "Service engine soon" light to go out.

However, I'm still getting cutting out and backfiring.

Probably dumb question: when I changed the starter and failed to seat that connector properly, could that have caused something to happen with the onboard computer? Is it possible that reseating the connector now did not undo whatever happened with the computer, and that's why I still have backfiring? Is there a computer reset?