My 93 NA lacks power and stumbles (lightly) above 2500 RPM's, especially when it is cold outside and the engine

is cold. I checked the MAF sensor voltages...

Voltage at idle was about 1.2 (0.8 - 1.5 is normal). Voltage
at 2000 RPM's was about 1.55 (1.4 - 1.8 is normal). Voltage
with ignition on and engine off was 0.43. Manual says about
0.8 volts is normal, so a bit off here. Any idea as to whether
the low voltage indicates a problem?

Other Checks Performed
-Changed spark plugs (Denso double platinum, properly gapped, normal heat range) - No difference
-Changed air filters - No difference
-Changed fuel filter - No difference
-PCV valves OK (good vacuum at valves, internals move freely, no sludge)
-Pressurized intake to check for leaks
-Replaced oxygen sensors & checked with ECU (rich-lean switch every second or so at 2000 RPM's)
-No trouble codes in ECU (checked multiple times over several hundred miles)
-Throttle bodies OK (cleaned 1500 miles ago, still very clean)
-Compression OK (~195 PSI with 8 PSI difference between cylinders)
-Cleaned most sensor and actuator connectors using electronic parts cleaner
-Checked fuel pressure (idle = 36, FPR disconnected = 45, light accel = 42-43, heavy accel = 45)
-Holds fuel pressure OK (No drop after 10 minutes)
-Vacuum OK (idle = 19 in, 2000 and 2500 RPM's = 21 inches, 3000 RPM's = 20 inches)
-Removed purge line from carbon cannister and plugged - No difference
-Coil pack resistances OK
-TPS OK (Resistance and voltage closed and wide open at spec, no dead spots during slow opening)
-Closed throttle position switch OK
-Coolant temperature sensor resistance OK (cold, warm, hot)
-Fuel temperature sensor resistance OK (cold, warm, hot)
-Detonation sensor resistance OK
-Fuel injector resistances OK

Anything else I should check?

i have this same problem, if you have fixed this issue PLEASE email me at jamminjman2002@yahoo.com
thank you

sounds to me like you've already checked everything, i have the same problem and have checked some of the same things you have, but nothing ever seems to work, aparently this problem happens often in the N/A Z's and none seems to have an answere for the problem, so who knows, if you do ever find out what it was please post so we all can know thanks