My 2001 Jeep Wrangler, 6-cyl., Sport model broke down two weeks ago without warning. Mechanic replaced the crankshaft position sensor. Ran like new afterwards. No previous problems with it - no blinking engine lights even after break down. Immediately after driving off mechanics lot the engine light started flashing (only after to 40-mph). Happened intermittently for a day, lasting about 10 seconds per batch of flashing episodes. Took back in and they replaced spark plugs + carbon clean-out. $300 later same problem. Blinking light intermittently. Blinking occassionally then turns to solid engine light that stays on and is on when car is turned back on. Mechanic replaced the "new" crankshaft sensor with another one, but both sensors were "after-market". Could that be the problem? Jeep runs completely fine! Even before the break-down there was no indication of trouble. Codes reading from the diagnostic since the blinking started suggest misfire on 4,5,6. Another reading on a different diagnostic machine showed irregular wave forms. Still, nothing running differently. Help!! Am I causing damage to cat.con. by driving with blinking light???