I have been searching for a fix on my daughters 97 Wrangler 4 cyl auto for awhile. Not sure if this was a prexisting problem, due to the fact i just bought this Wrangler with a bad engine and it had been sitting for 3 years. I Replaced the motor myself with a remanufactured engine. Pretty easy job if you have all the tools. So it runs well, no missing but the check engine light repeatedly coming on after a few miles, code read 1391 which is the cam sensor or crankshaft sensor not sensing. Replaced both, still not fixed.
Got to the Point it was time for a professional assessment of the problem. Took it to a small local shop I felt comfortable with. The tech said the 1391 was caused by a loss of communication with those sensors above 1500 rpm's. He just needed to find out why.
While trouble shooting it, he noticed the distributor has excessive lateral play in the distributor shaft. Only had 71 K miles on it.He Installed a remanufactured distributor. Problem fixed. California smog passed also. So happy.