metro fuel pump?

Here's one that's got me stumped. My 1997 Metro (4 cyl) will just cut out while I'm driving. The problem is intermittent, and seems to be worse when the car is hot - after about 15 minutes of driving. It acts as if it isn't getting fuel - the "jack rabbit" effect. I cahnged the fuel filter, plugs, and the throttle position sensor, but the problem persists. A mechanic I know pulled the codes off the car and said they only indicated it was "related to the throttle positioning sensor." Would that include the fuel pump? Is there another part that could just shut the gas off at odd times? The car starts easily and usually idles well. Also, the problem doesn't get better or worse on hills. Some advice or information would be appriciated.