I've been using WinALDL over the last few weeks too, and I must say, it's been handy. It's also just kind of neat to see the data going by and what the ECM is up to. Came in handy for adjusting my TPS.
I've got a 1989 Camaro RS with the 1227302 ECM and the 1985 2.8 MPFI setting does seem to report more accurate results on a few sensors (BAT voltage, Rich/Lean counter if I remember right), can't remember for sure though. The 1986 2.8 MPFI setting shows spark advance though...
Also, on a side note, I put a Holley Ignition Control Module, MSD Blaster GM, and MSD Superconductor wires on my '89 RS this last weekend. Also replaced the TPS (could not adjust previous one below 3.2v at zero throttle!). The car idles and starts SOOO much better now. It idles smooth, starts great, and I THINK there may be just a LITTLE extra ooomph (may be in my head too). Up next, Dynomax!
-Jason
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1989 Camaro RS, 2.8L V6, 5 speed, T-Tops, 87,000 miles
1987 Camaro SC, 2.8L V6, 5 speed, T-Tops, 128,000 miles