fact that the micro-tech maf did not throw a code when two bosch sensors did tells me that micro-tech is not reliable, i'd trash it.
code should be tracked down and fixed...this does not look as simple as some, but there aren't really that many components in the whole maf system -- a maf sensor (which you have already eliminated by parts swapping), the relays (also eliminated)...just leaves the oil press sender, the ecm/prom and the wiring harness.
weird prob that i saw on three diff cars last spring (never before that,none yet this year-- spring roll-outs are delayed here by cold) was a single terminal in the ecm connector had corroded away to the point that no contact was made, all three ran poorly...diff pin on all...pita is that you must back the pins out from the connector body to see the prob, the end of the pin as seen by looking at the connector looks ok...to do this check on your vette, remove the pass seat, put your feet in the rear luggage area and your head on a pillow where the pass feet belong -- the connector will dangle in front of your nose when pulled from the ecm...you need a pin release tool which you can buy or make from a 16d nail--file the end of the nail square o.100''x o.100''x 3/4''long...push the individual wire connector wire INTO the connector before you insert the release tool, then pull the wire/pin out...replace good pins immediately back into their correct cavity to avoid mixing.
