Running out of options

I have a 1987 Pontiac Grand Am and lately have had a recurring problem Started 6 months ago: while under load (going uphill, etc) it sputters, coughs, chugs, etc). First my mechanic replaced a fuel injector, then found a wire shorting on the block, then another time replace a throttle module (I think). Now it is back in the shop and he is stumped. Anyone have any ideas??

When was the gas filter changed? It seems to me that the car should have stopped running by now if it is a clogged filter, but it’s cheap if it works.

Not enough info known to make much of a guess but has he checked the lowly fuel filter?
This could cause a problem with the engine under load; much like a clogged catalytic converter would.

This sounds like typical symptoms of fuel starvation under load. Or perhaps inability of the engine to expel the aded volume of exhaust that it needs to when under load.

The aforementioned suggestions of the fuel filter and the exhaust syetsm are good ones. I think I’d go further and check the fuel line pressure.