Found the problem. well actually a couple problems. Your mechanic is going off "should be" and not the specification which is 48-52 at idle and when you blip a boosted car you should see 60-70psi, not a drop off. When the pressure went down, that should have been a clear indicator that the pump is not keeping up with demand.
Add another problem actually. Coolant or oil pooling on the LIM does not cause a multiple misfire. At most a bad LIM gasket may cause one or two cylinders to misfire, but this is extremely uncommon. Usually you never know your LIM is bad until you pull it. Pooling on top is a simple leak, not something that is getting into the cylinders. When we think about what is going on with a motor, it is important to think about how things work and if A equals B or if C is involved.
Problem 1: Mechanic
Problem 2: Fuel pump
Problem 3: Misdiagnosis
Originally Posted by XEN
Today the mechanic checked my fuel pressure in was in the range of 45 when reved it went to 35..they changed the fuel filter