1999 F-150 S/C 5.4L with 70,000 miles. Stalls on cold start and will not idle. Once warmed up runs great. Cleaned Throttle body/butterfly area with carb cleaner and toothbrush reaching in as far as I could. Works for about a week and problem returns. The truck has not seen the dealer since the day I picked it up. First problem I have had.

Thoughts and Ideas?