Problems with stalling on car while in motion

Good morning all! I have been having a problem with my 1991 Buick skylark stalling or sputtering while in motion. I got this car from an elderly woman who only drove it 55,000 miles from 1991 to 2010. When I got it naturally the brakes were in bad condition as well as the hoses. So all of that has been replaced. The belts, wires and plugs have been replaced.
The car will completely stall out only when I begin to slow down. It will sputter while in motion and jerk while on the interstate. I consulted my brother-in-law and he suggested that it was the catalytic converter. So, I took it off and while it ran quite a bit longer without issues it did eventually stall out as I was getting off the exit ramp. It will start again and run after I let it sit for about 20-30 minutes. Anyone got anymore suggestions as to what may be the problem. I was thinking the Oxygen sensor may be bad. By the way, the temperature gauges never come on to tell me that its overheating and I am not losing water/coolant. Thanks for your help! :runaround:

Which engine?

Since it takes awhile to restart, could be a fuel pump on it's way out, or electronic, like a crank sensor....

Best time to check is when it won't start....check for fuel pressure, spark, and injector pulse....

Didnt think about the fuel pump... it is a 2.5 L 4 cyl. Thanks!

It could also be a vacuum leak with the PCV system. Change the charcoal cannister too. It probably isn't the problem but it's an overlooked part that should be replaced every 60,000 miles.