Ive noticed in the morning when im leaving it feels like 1st is slipping. Reverse is fine but when i put it in drive and take off it seems like the truck is so hard to move and im on the throttle more to get moving. After it shifts through the gears a couple times its fine and takes off normal. Could it be a solinoid sticking? Im not sure how many miles are on it the truck i pulled it and the engine from had 315000 but engine was replaced 90000 ago im not sure on the trans though. It shifts good and doesnt slip at all after this happens and it doesnt slip in any other gear but 1st.