1992 Chevy Lumina

Engine Mechanical problem
1992 Chevy Lumina 6 cyl Front Wheel Drive Automatic

I have a stalling issue. The car was starting up fine and then would stall on a turn or when accelerating after a stop. IT would start back up after a few mins. Repair shop had it for 10 days and couldnt figure it out. Didnt get any codes off it and cleaned evrything they could. Said they cleaned the injectors and the tps connections. I changed the fuel filter but not the pump. It checked out on the repair shops monitor as fine and I can hear it run when the key is turned. I let it sit for a few weeks and now it is very hard to start and when it does, it will die when I push the gas pedal. I could use a little advice before I start replacing anything else myself.