sounds like they've thrashed it and fucked something up then tried to cover it up.

i'd hazard a rough guess they've split one of the (small) boost pipes on your amal valve by thrashing it, then replaced them all but not replaced them correctly. check them all.

lmpy idle would also indicate a small airleak.

dont replace the fuel pump, you dont need to. they usually either work or they dont, its lasted 20 or so years under your car in the sun, rain, snow and salt. trust me its fine unless its making a loud grinding noise.