Ford Repair: 2001 Taurus Rough Idle, vacuum leaks, dirt dauber

Question
Hi Mark,
recently purchased (from a family member as a favor....) a 2001 taurus. This vehicle sat for 4 months after having fuel tank replaced. It ran poorly so I replaced plugs, wires, all filters, belt, etc. It still has a very rough idle under load (in gear), but runs smooth, has plenty of power, etc on the highway. I have checked for vacuum leaks,replaced coil pack which was firing weakly) checked compression on front cylinders #4 125, #5 150, #6 160. Evidently they put a used tank in, so I wonder about dirt, debris, etc. I have run two tanks with injector cleaner. I also believe there's a vent problem with tank as it takes forever to trickle fuel in.

Answer
although sitting isn't good for a car at all four months shouldn't be that bad-i would run a fuel pressure test make sure you have at least 35lbs at idle and not over around 42lbs-are you sure it is a running problem and not some type of vibration like possibly trans problem say maybe torque converter-do  yourself a favor and have it checked out.
i agree with the vent problem in the tank who put it in? if at a garage have them recheck it if it was used it could be something as simple as a dirt dauber clogged hose-and i don't warranty any problems on a used part whatsoever so find out their policy. good luck.