Acceleration issues when warm

What is your question?

I have a 1988 Ford F150 custom 5.0 When the engine is cold like in the morning, it accelerates fine but when the temperature outside starts to warm up or the engine is warm, I can still accelerate, but the truck barely moves. RPMs will be very high, but again I barely move sometimes when it’s warm, I can even put it in gear, it’s a manual and I can take the clutch up and it won’t move and it’s in gear so I need your help

What makes this problem better or worse?

It’s worse when engine is warm

How long has your 1990 Ford F-150 had this problem?

1 month