Adding this to the forum because one day you may be there too. I have an E-350 with 49980 miles on it [yes, 20 miles till expiration of factory warranty]. At any rate...whenever the car sat for >2 days and then got started, a loud chirping noise eminated from the engine for about a minute. I once left it sitting for 5 days and upon start, chirping lasted for 10 minutes...lifters, pulley? Nope, the Serpentine belt was "glazed over." Problem solved..