1999 Jeep Grand Cherokee Backfiring

I have a 1999 Jeep Grand Cherokee that when you start and put in drive, it will feeling like it is stalling and sometimes backfire. It does this until I step on the gas and go fast for a couple of seconds. After that it is fine until I start again alter in the day. There were no codes when the garage checked. Any ideas??

Backfiring means unburned fuel is leaving the motor.
Make sure basic maintenance is up to date, especially ignition parts.
Replace the coil and plug wires if original.
Check ignition timing and compression.

Same thing as my 1999 Grand Cherokee. Check engine light came on. I looked it up. New plugs did the trick.