The preheater is directly under the carb. I don't think this alone would be causing the Jeep to not start. Older cars didn't have 'em, and they started up.
If the chokes closin', and the spark is sparkin, she's turnin', and she's got gas, she should start, or at leat buck or something.
I have heard stories of the howell having problems with different program chips, and the MOPAR MPI giving pinging a lot.
I'll keep my HEI and Weber.
88YJ, 4"susp, 33"BFGMT, 9k#winch, rear homemade swingout, reb.258, 999, 4.10, weber32/36, GMHEI.