Engine starts and quits... will not continue to run on its own... must use gas pedal to keep running until warmed up.... then it runs just fine. Have had dealer replace pugs and wiring harness, clean injectors and replace the part that mixes the air and gas... their diagnostic equipment does indicate any problem... they're stumped... up to now I have been confident in the work they performed. Any suggestions as to what the problem could be?... anyone had this same problem?