Could water absorbed by the fuel cause problems like you are having?It runs fine until it warms up) Does anyone know if the 'wet' fuel changes properties in a hot carb.?(I would assume that the water could turn to steam in a hot carb/manifold) Another thought along the same line - If the engine was tuned to being cold, could it be re-tuned to run poorly cold, and run well when hot?
I believe it is a problem isolated in your truck, or many people would be experiencing the same problems.
