i hadn't changed my spark plugs since i got my truck, and it was doing the same thing. got around to doing the tune up, let me tell you, my spark plugs were horrible, their was a rubber tip on the long tip of the spark plug. i don't know what the hell it was but apparently it wasn't getting spark to the motor.
Lol my plugs in my 4.6 were from 98 I found out and they were burnt up so when I put in the ngk's I felt a big difference
I don't know much about the newer 3.0 and 4.0 motors but I think that you only have one coil pack. If so, that's about right for a shop doing it.
Man, he needs to learn to do that repair himself. VatoZone sells the single coilpack for the 4.2's for like $85.