Engine Problem

Hi Guys first post so please be gentle, I have 2003 1.8l duratec petrol Mondeo. Over the weekend I had a problem starting it at first it would crank over but not start I banged the rear filter a couple of times and it started i could feel the filter vibrating but couldn't before that, it was fine for about an hour driving around, but I parked it up and about an hour later went out to try it again this time it would start but as soon as you gave it gas it felt like there was nothing there and it would cut out. So i left it and tried it again Sunday morning it started first time and the revs were fine. got it to the garage today he said it was the pump so got him to fit a new fuel pump and filter. Rang him earlier to pick it up and he,s now saying there is a problem with the power that when he puts his foot on the gas there is nothing there and it was idling at 500rpm he's now saying he thinks it my MAP sensor cos it was loose and coverd in gunk, but there was no management lights on before and no lack of power, think there might of been a slight what felt like the throttle was stuck open like if it had cruise control in that if I took my foot off the gas I could just cruise at that speed until I touched the brakes? this problem wasn't there before he started am wondering that when he had the tank off hes knocked some gunk back into the tank and now its been sucked back into the pump and clogging it up any idea's thanks because a £140 job has now turned into £210 without the sensor.