1995 Buick Lesabre problems

If problem under load, usually a restriction of some kind, check air restriction-- check fuel pressure-- check clogged exhaust. You could check throttle position sensor. As far as checking for trouble codes, 95 is a cross-over year, if you have a hybrid datalink connector, I can't help you with that type connector.

If your datalink connector is 12 pin and your fully obd1 compliant, you can check codes, yourself.