I recently purchased a 2002 QX4 with 170,000 miles from a friend. It had been sitting for about a year and when I first took a look at it we jumped it and it started fine. The first thing I did when i brought it home is put a new battery in it. After driving it for two or three days I noticed a slight hesitation to start, which got progressively worse over the next two days. Eventually, it stopped turning over.

I purchased and installed a new starter and it started without a problem. However, after installing the starter I went to the store and when I tried to start it again I noticed some slight hesitation to start. This got worse, to the point now where it starts in the morning, generally I have to crank it for a few seconds, stop and repeat a few times before it starts. It will not start when it is at operating temp (it may start but I end up cranking so much that I dont want to risk damaging the starter and draining my battery). Once it starts it runs great. I am getting EVAP codes but I do not believe they are related to the starting problem. I am not getting any other codes.

I replaced the MAF and it didnt change anything.

I noticed that my temp gauge goes up to operating temp very quickly; after about 1 minute of starting the engine. I cant imagine the engine can reach operating temp that quickly, and considering my starting issues seem to correlate with engine temp I am thinking the engine temp sensor may be bad? Is there one temp sensor that sends info to the ecu and the gauge? Or are they separate sensors? I also noticed that the coolant is low. I am going to top it off with some distilled water today and see if that helps (Ill do a coolant flush once I figure all this out).

I bought new plugs, air filter and fuel filter. I am going to buy the temp sensor today and get all that installed this weekend. Any suggestions would be greatly appreciated!

Thanks,
Tim

Welcome aboard!

Sounds like you're tracking correctly, the ECU is seeing a hot-start condition. The sensor SHOULD address it, but that's not always sufficient.

My next steps would be to remove and clean REALLY WELL all the connections and grounds. I mean, get to shiny bare metal, and reinstall. This should include starter connections, battery terminals, body and engine grounds, and alternator wiring.