94 2.2L Shadow Cuts out while driving.. Help!

I have a 94 Shadow 2.2L that will start in any weather, cold or hot, idle decent. a little rough at first, but it smothes out after 2 min of idle. The problem comes in after you drive the car about 5 miles it'll start cutting out and having no power unless the gas pedel is depressed completely to the floor and the tranny shifts down. If you hold the gas pedel as if you were driving at normal highway speeds the car will act as if the engine is off and it will pull the car down in speed.. if you pump the gas the car will keep up to sleep, but will constantly cut out and run spuraticaly. Driving above 75 mph , the problem goes away as the engine revs high enough to keep the problem from occuring. putting the car in N while coasting down the road you can rev the engine and it has no problem reving up, just will not pull the car unless its reved , or the gas pedel is constantly pumped. I have already replaced the MAP sensor as i was told it would be a common problem. any suggestions?

sounds like a throttle position sensor going bad.