Some times when releasing clutch. It engages almost instantly. Then after a few shifts it is back to normal.
I would say one of three possibilities. A fluid leak, bad slave, or bad pressure plate. Put truck into highest gear and pop the clutch, see if the engine stalls. If it does, your plate is fine. I would check for leaks or a bad slave cylinder. If you've done work to it lately, you may have air in the system as well.
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