I have a 1999 Chevy Tahoe that has been acting up lately. It has been taking longer to start than usual and over the past 6 months it has been backfiring which sends a huge cloud of smoke rolling from under the hood and when it happens it does something electronically and resets my radio clock back to 12: 00 each time. Today I was running errands and noticed that it was idling very high while it was in drive. I literally had to ride the brakes in the 30 mph speed zones. Got to one of my errand locations and it would barely start. I got it home and it cranks over but will not start at all. I'm wondering if this is an electrnic issue and not so much something mechanical. Any ideas?
The first thing I would do is clean and tighten the battery cables. It sounds like you might be losing voltage to your electrical system. You might have some other problems too, but this is the first thing I would check.