What's going on with my truck?

My 2006 F150 starts normally and goes right into high idle the way it always has. But when I put it in gear, it doesn't want to go. It sputters and coughs and won't accelerate. But once it's warmed up, the truck can be driven, even though I can still feel a slight hitch in the engine. It acts like a... show more My 2006 F150 starts normally and goes right into high idle the way it always has. But when I put it in gear, it doesn't want to go. It sputters and coughs and won't accelerate. But once it's warmed up, the truck can be driven, even though I can still feel a slight hitch in the engine. It acts like a malfunctioning choke, but I'm pretty sure fuel injected engines don't have chokes. Any ideas?
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