2003 Hyundai Santa Fe Stalling when gas pedal is pressed.

My 2003 Santa Fe stalled out a few weeks ago while driving. While going up a hill, the gas pedal was pressed and it just stalled out. It will start up but seems to be idling quite hard. We can drive it, but only about 5 mph around a parking lot and it wants to stall each time. It has been in the shop for over 2 weeks now. The mechanic said that the fuel pump was only putting out about 10 psi which is obviously deficient. He replaced the fuel pump but that still did not fix the problem. He is checking to make sure the new fuel pump is not faulty. But aside from that. He can't figure out what is wrong. I told him in the first place to check the crankshaft position sensor but can't guarantee he gave that a second thought. No codes are being given.