It's the crank sensor!
Join Date: Nov 2007
Location: Central Minnesota
If you have a check engine light, unless you stumble onto the problem, the best bet is to get the code read so you have some hard data to go on. Use the OBD2 technology on your 99.
Some of the big box parts store (Advance Auto Zone) will plug and read your codes for free in the hopes that you will buy necessary parts from them. Otherwise, any shop can do it and shouldn't charge you much for just reading them.
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!