TA1217

i left work and drove half mile to a gas station. ever since i got gas its ran for ****. it will idle high at cold start. but here's where it gets weird. Its an auto and when i slow to at a light and hit 4-5 mph outta no where the RPM drop to about 400-500. it has a mail in tune from texas speed and have had it for over a year since the cam swap and tune. it drives fine, doesnt seem to lack any power but something to do with the RPM being 1200 or less it starts acting crazy. ( when i crusing but not all the time. just a miss here and there) i tried cleaning the throttle body and sensor but no luck. also tried pulling codes and once again no luck. PLEASE HELP i just started my new job and need my car for monday!!!