i have a 01 2.8 FWD and the engine takes a really long time to reach the "middle" normal temps. driving it for about 8 miles after a cold start and it will reach normal temp.

also the temp is not stable. the temp fluctuates from the middle and moves to the left if the ac is not on. it starts getting cold. does not get hot. BUT if ac is on the temps sticks to the middle like my other 2.7. but whenn the ac is not running the gauge will move back and forth from the middle and cool down and back to normal and cool dwn ect...

there is a check engine light on. BUT i cannot see the code because the ecu will not communicate. i have checked the mats under the passenger side and no water..

 

When was the last time you checked/changed your thermostat?? It might be "sticking". Or it is stock open at all times. Look into that first.....

 

Possible Engine Coolant Temperature (ECT) sensor acts up.
The little green monster.

Mine broke and triggered CEL. Syptom is the needle didn't go to the middle in normal timing; once it went to the middle will come back down to C area again and stay there.

 

my cel comes on and off. but recently it has been coming on every 2 weeks and goes away after a good 100- 200 miles. usually it came on once every 2 months LOL. i pulled a code when the ecu was working and it was something to do with the coolant temp. im getting a timing belt done in about 5k miles so i was thinking of letting it be for now

 

If it is the ECT, my 2002 is located on passenger side between the engine back and the firewall, covered by a bunch of stuffs.

 

I would have my 2 cents on the stuck open thermostat.