1990 Taurus Wagon lack of power on acceleration

Could be many different things. Plugged exhaust/cat, plugged air filter, plain old worn-out engine, just to name a few. I myself would change the air filter and have a compression test done on it. Also, have you ruled out some of the easy ones, like the parking brake being engaged? Does it run rough or sound like it misses? Plugs and/or wires may be in order if so. I also assume you ruled out crappy fuel? I'd check the fuel filter also. If you take it to a mechanic to get a compression test done, have them check for vaccuum leaks also.

As far as checking the exhaust system integrety, I'm not sure how a person would do it without just replacing it from the get-go,,, which is not a wise move due to the amount of money it would take, and the fact that it's not 100% for sure the problem.

BTW, when driving through Canada in a '91 tempo, I experienced similar conditions, turns out the floormat got bunched up under the gas pedal. Could you be so luckey? Check it out.

Well...it's been doing it for a long time now. I'm certain it is not the brake or anything like that. I suppose a tune up (replace the plugs, new filters, etc..) might help. I'll give them a try and let you know how it works.