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.

Have been having same problem. With car sit they took to dealer replaced about 4000$worth of parts then offer to buy when could not fix.Remove air cleaner. The throttle position sensor >is under where air comes in, rubber boot w/clamp wire goes toward fuel pres regulator (4)prong>make sure air line from valve cover (where air cleaner hooks to valve cover) that line goes to fuel pres.reg.> idle control valve (3/4 line in and out) is close to F.P.R.
OVP (over volt.prot.) is behind battary has (RED)top 2 fuses (or-1) push in tipe (gm) 10 amp. Don't feel bad have 5 hrs trying to fix one i am working on.its goten better but no silver star yet.been working on benzs 28years know Worker on 8-9 300 from 50's i love working on them this my 3rd 88-91 300.What nice for me is have 89-300 parts car,300 engine out of car ran good blown head gasket. So i can swap parts 3sets of wires cap rotor>coils>control boxes>conplete fuel systems. Hoping to day to fix.