I still can't find a reason for my truck to be making a pecking noise like some thing hitting the fan.

to answer last persons comment.  Fan shroud was loose but was tightened, so it isn't
that.  Noise started after mechanic worked on my truck it was running smooth before
water pump was put on , serpenteen belt, and throttle control sensor for it charging
when my foot wasn't on the gas.  It doesn't want to accelerate when I first take off at
the end of my street, sounds like it is racing but doesn't want to go, both these things
started next day after work was done.  This noise I am hearing sounds like something
hitting the fan or fan hitting something when I start it up, pecking, but can still hear it
when sitting at drive up it doesn't completely go away is worse when I start it up or let
it sit for at least 3 hours.  No one can seem to tell me what this is I am worried, one
mechanic said air intake volve, one said the shroud that was tightened, the one that
worked on it said dry belt put a new tensioner and belt on wasn't that, no one seems
bothered except me, and they want to keep charging me money to tell me something
different, but it isn't fixing the problem this is my only means of transportation, and I
am worried some thing was done when it was worked on, and may cause me major
problems, and I have to drive across country soon.

Thanks,