engine was perfect at 2002 season end. Tuned up in spring 2003, first trip out engine skipping, and stalling out more so when rpm's advanced to 2000-2500. Repair done with changing throttle sensor, and remapping? it. One trip out it worked great, 2nd trip out back to same problem.

Do plugs get fouled as soon as engine skips?

Engine runs ok up to 1500 rpm, is it ok to use?

Any thoughts on the above scenario? Thanks