do you have acces to a scan guage? this way you'll be able to watch short term fuel trims, i'am thinking your injectors need to be considered.

id take it easy on the gas pedal and major loads... that popping/backfiring is detonation which will lead to really bad things such as a thrown rod, or burned piston and valves.

the check enigne light on the dash was flashing? not the O/D light