1989 Gas 300E Severe Hesitation

[yadawho]

My old retired parents have a 1989 gas 300e, the problem is that when you apply more than a slight amount of throttle the car falls flat on it's face, severe hesitation, this happens at all speeds, it does not happen if you power test it in gear with the brake applied, it will start to spin the tires, the car has 150,000 miles and had the original spark plugs and wires, which I changed, I also changed the fuel filter, but not to try and cure the problem, but as a matter of much needed maint. I know nothing about the type of fuel injection system used on this engine, I seem to remeber it has a fuel distributor and a door that is pulled open by engine vaccum, is there anything like a throttle position sensor or any other sensor that could be defective or out of voltage tolerance? If anyone anwers this please use plain language, no abbreviations for componets please, I sure hope I can figure this out with others help, my parents are cash poor and my help is all they can afford.