1993 Pontiac Trans Am Feels like no gas, or starving for ga

I own a 1993 Pontiac Formula Trans AM or FiredBird with the LT engine in it. I can get in the car and start it up and drive for days or hours, then the engine acts like it is starved fo gas. I had the catalic converter replaced thinking this was the problem, however it was not. Used to be able to run it poorly to the X-Way and get up to 70-80 miles per hour and it would strighten out, Then some days after shutting off the problem would start again. Back in the late 90's I was washing the engine off, and since that time the problem began. Is there a chip in the engine that can be replaced if it is bad, causing the engine to run bad.