Clean the MAF, then make sure the fuel filter is not old and clogged, then check CO.
It is just coincidence about the VSS, although they are linked, I would also clean the idle speed control valve, with it now getting a decent VSS reading the mixture will be different.
All you need to do to reset the ECU and put it in learning mode is to pull the KAM fuse for 5 minutes.
tabetha