My car starts and run but when warm or put into gear it dies if you dont keep on the gas pedal the timing sensor but not for sure 1991 buick regal 3.1

Mass air flow , crank sensor . I wouldn't discount anything . Having a scan tool that can view engine sensor data would be a great help too , testing fuel pressure and flow and back pressure test the exhaust .
058 Engine Hard to Start or No Start Lean Fuel Condition
055 Engine Hard to Start or No Start Scan Data for EGR
057 Engine Hard to Start or No Start Ignition Module Test
007 Catalytic Converter Testing

check your cam position sensor and the electrical connector first. you may have a bad sensor. if the sensor is good, then the timing cover has to come off. if the timing cover has to removed be sure to change the seals, timing belt and timing belt tensioner while the cover is off so you won't have to re-visit the same area later.

Your battery could be weak, Do you still have the original battery? You can get a new one at basically any auto parts store.

mrmac9956 your festiva sounds is if it needs a tune up ..

replace the ignition module,under the coil pack.

Sounds like a vacuum leak crank sensor fuel pump stuck EGR valve

Have you done the basic maintenance. Spark plugs, oil change, ect.? As for the fans, if you have a/c one of them should only come on when your a/c is on. The other is regulated by a relay so when your car reaches a certain temp it kicks on.

unfortunatly it sounds like you are having issues with the torque converter. it sounds like it is locking up all the time now. this requires the transmission to be taken out to change it i do not know what your experience is so not sure if you have the tools or knowledge to do it yourself.

Replace the timming chain, gears, and magnet. With that cat getting that hot it has to be out of time. When the cam sensor picks up no signal, ecu can't control timming and reverts back to a preset,fixed base # .

Check to see if you have a lot of dirt in the throttle body. Clean the throttle blades out with brake cleaner or throttle body cleaner. You'll see alot of dirt come out. Keep spraying until it comes out fairly clear and wipe the throttle body out with a rag. If this doesn't do it, you may have a problem with the throttle position sensor (TPS). This sensor controls the idle after the car warms up and keeps it from dying when you brake or sit at idle.