Sorry to hear about all your issues! So are you still receiving an error code (PO301) and is that the one and only code you have? Since you have read most of our posts I suppose you have reset the Nitro computer, too. I know it seems far-fetched but how about your battery? They can go bad and cause all kinds of problems.
Dodge Nitro :Battery issues?
If you are only showing the PO301 error code is that what we need to focus on only to address and get your Nitro back to 100%?
Let us know and see what we can come up with. Good Luck!
Nitro Year: 2007 (1 of 91,815 sold in 07)
Nitro Model: R/T 4X4 Stone White
CAT-BACK Exhaust, CAI, Projector Head Lamps
Fully-Equipped w/all factory options