Had a similar scenario with my '01. The timing belt had skipped a tooth or two on one of the cams. Don't know if the '96 models had the same trouble codes available as mine, but the garage pulled a cam timing code out of it when this happened (bought a code reader after that, it has paid for itself 10x over by now). Don't know why I'm posting this, as it's likely an exhaust issue, but the thread title reminded me of that incident.If all else fails - try the cam timing.
Good luck.

If I had a hammer.....