High gear problem??

I have a 2001 automatic, LE neon, I was driving normally at a highway, and suddenly after some time at 60 m/hr, the velocity started to drop, even if I pushed further in the gas pedal, it only elevted the RPM, but velocity continued going down, I sotpped and it would feel as it would shut down but it didnt, and after that it was very difficult to have the car going, even at low speed. Shut it off, and after a few minutes it started normally. I took it to a mechanic, and he says it is the fuel pump, even after he shut down the cars fuel pump, took off the pumps relay and placed a recipient with gasoline and pressure directly to the gas rail, and at above 3,500 rpm it continued with the same problem, the engine starts to jerk every 1-2 secs,:banghead: :banghead: :banghead: :banghead: :banghead:. Below this 3,500 RPM, the motor does no abnormal movements, I thought that this would take the fuel pump out of the possible trouble diagnosis, and after reading some other threats & the Hanes manual I would think its the TPS.
Is the mechanic trying to charge me more by changing the pump, or could it really be it?
Or could it be the TPS?:confused: