1985 245 DL driveability problems

I have a 1985 245 DL US spec, manual trans, that has an intermittent driveability problem...runs great 98% of the time, but occasionally loses power...runs smoothly, but the harder the accelerator is depressed, the more it bogs down. Turning the ignition switch off and back on instantaneously almost always resets this. But sometimes it runs much worse, with almost complete loss of power, terrible backfiring, and difficulty restarting. Temperature does not seem to be a factor in either of these symptoms. I believe both fuel pumps have been replaced, and possibly the spark control module. I was thinking abouit pulling out the ECM to check for bad solder connections but other than that I'm baffled. Is this a known issue? snipped-for-privacy@juno.com