So I have 2003 XK8 converitable that up to recently was fun to drive. Couple months ago the transmission started hard shifting from 1st to 2nd and 3rd to 4th. like hesitating type shift. no noise that ive noticed. but latly it still shifts hard but when going from 3rd to 4th gear itll lock up like it was thrown into park! and engine shuts compleatly down i put it in nutral cost to safty (if im lucky not to be in traffic) and shut the car compleatly off, and issue solved. for a bit. but when i notice the hard shifting andit doesnt lock up.....I pull over and turn vehical off and issues is usally solved. Any suggestions?

 

An engine fault will upset the trans so first use an OBD tool to:
1. check for codes (DO NOT clear them)
2. check fuel trims (see the many threads)
3. check whether you have P1000 or P1111
4. if P1000, check status of OBD monitors

 

Another 2003 owner had the computer reflashed to solve a hard 2>1 downshift