Why would a timing belt jump time and cause damage to the cylinder heads ?
No. A worn timing chain or belt would cause timing to jump.
sometimes and it has a belt
I would suspect you need a new timing chain or belt depending on which is installed. A worn belt or chain will jump time.
The timing belt can only jump time if there is a failed component in the timing belt system. Check the pulleys and tensioner.
Timing chain or belt is broken
Loose timing chain or belt.
Timing belt. misfiring engine
The belt could be wearing but not show any problems. When the belt stretches the timing will jump and the engine will run rough. If the belt breaks then the engine wont run at all.
Every 90k miles just like a timing belt. You can go over but it will stretch and jump teethes screwing up your timing.
A sloppy, worn out of adjustment timing belt.
You may have a timing belt missing a tooth or two, or a worn out timing belt tensioner.
They have a timing chain, and it IS a interference engine. So read-up before you jump in!