My project truck has been sitting in the garage for the past few months. I havent had much time to work on it, or drive it for that matter. Every couple of days I pulled it out of the garage and let it run for a few minutes.

Anyway, I pulled it out this evening and took it around the block. The transmission will not shift untill redline when in drive. If you shift the transmission manually it will shift whenever you bump the lever. Any ideas on what could be messed up. Some sort of filter? The transmission was rebuilt 7k ago, and worked perfect when I parked it a few months ago.