O8 dodge grand caravan stalling after transmission replaced

Hello my 08 dodge grand caravan with a 3.8 liter engine is stalling out after my husband replaced the transmission. It's doesn't start stalling until the engines warm. Does anyone have any idea what bit might be? We replaced the throttle body and also ran cleaner through it we replaced the air filter and sparkplug and wires. It isn't throwing any codes and it only stalls when coming to a stop.

Thank you