I like your approach to the MAP and O2 sensor.  Regarding replacement parts, the only O2 sensor I use is Mopar-packaged or the OE supplier.  On my 4.0L XJ Cherokee, that supplier was NTK, and I could match the OE sensor's part number to an NTK item. You commented on your experience with engine cooling fans.  There are some aftermarket pieces that work, but electrics, and especially sensors, seem best when OE sourced. As a footnote, I've had issues with an O2 sensor, CTS switch and a TP