The stock sensor is narrowband (only reads accurately in a narrow "band" of A/F ratio values). It will never read accurately outside of that band. MS can understand narrowband sensors, but they are only useful around an A/F of 14.7:1. No amount of software can fix that. If you want some decent A/F data for cheap, buy an Innovate LC-1 (less than $200 with sensor). It outputs full wideband data and uses an affordable sensor. You can buy or make a gauge for it and/or hook it up to the MS for datalogging.
As far as EGTs go, I suggest you get decent quality gauge and sensor. An Autometer gauge like 5743 is decent. It reads 0-1600F. I don't think there is a need to have a gauge that reads to 2000F, unless you need to differentiate between melted and really melted pistons. Get a separate probe like 5244 and you end up with a better quality product. The probe has a long braided cable and connects directly to the gauge. Cheaper probes have intermediate connections that can add error and non-braided cables that are more delicate.
