CODE 42 - 1992 Astro

Is there any chance that the +battery cable to the starter
could cause a Code 42 Trouble Code?
When the van gets hot from driving it will backfire (and sometimes stall).
It restarts fine but shows the Service Engine light.
The light stays on when I restart the van if it's hot from driving,
but when it cools down after being parked for a couple hours the light
doesn't come on when I start the engine.
I might drive 200 miles before it happens again.
I changed the starter the day before going on vacation
(drove 1800 miles round trip).
After about 500 miles, The Van stalled on the highway 3 times and
backed-fired 6 or 7 times during the remainder of the trip.
I get Code 42 (elec timing circ) when I jumped terminals A & B.

Could my positive battery cable be grounding out somewhere by the
starter solenoid ? I really shoved the thing up there when I installed it.