I have a 1998 chevy silverado c1500. I have a problem with my transmission. When the transmission warms up it will shift hard to first gear and second gear. All the other gears shift fine. The first and second gears will shift fine when the transmission is cold. I done changed the transmission fluid and filter.

 

Welcome buddy! It could be torque convertor slippage and ignition switch solenoid failure. Maybe have your trans full scan.