It's not likely that the ignition computer is bad, or that the spare is bad. If you had another 85-88 car around, you could try yours in that one to be sure. I'd be *much* more suspicious of the wiring harness to it- it goes under the front pulley on the engine, and it's the source of numerous headaches. Try simply moving it around, bending it, repositioning it. It could well be shorting out internally if wire insulation is shot. Are the wires on and around the engine showing signs of deterioration? Usually you see it at the alternator, at the big gray connector on the firewall, and around the intake manifold. If so, I'd plan on a harness replacement- not a real fun job but unfortunately a common one for these older cars. My '86 is due for a harness now too- I'm putting it off until I really have to, and not looking forward to it. Good used ones can be found but are not easy to find. Nwe ones are a bit expensive from the dealer, so I'd make a few phone calls before deciding to take the plunge.
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE: 625K total