Hello new here. I'll start with a little history here. Have had my wife's '04 Endeavor for a few years now and it was in the family before that. It is now at 172k miles. My mom put the first 140k or so on all highway, but she never used premium fuel. My little brother had it for a while after that and it was driven pretty hard. 18 year old kid street racing it, go figure. In their time with it the serpintine belt(s?) were replaced twice from knowledge. All spark plugs and 02 sensors were also done at some point between 100-150k miles. It has been very reliable, but has developed a few issues lately. In colder weather (less than 30*), while in gear and stopped, like at stop lights, it will sometimes stumble. Rpm's drop to approximately 500 or so and then will gradually pick itself back up. New battery and air filter fresh oil and filter seem to have helped but the problem now seems to happen only when you flip the heat ouput to defrost. I was thinking it's probably time for new plugs and 02 sensors, clean throttle body and intake sensors(Map? MAF? IAT?, could use some advice here).
Upon researching this site, it looks like we should be doing the third timing belt about now so I'm really impressed, and lucky, the original made it this far. I have found a few "Timing belt kits" including- timing belt- tensioner- idler and tensioner pulleys- water pump and gaskets- serpintine belts- camshaft seals. This seems like a good way to go with this mileage and lack of attetion. Any other recommendations at this point?
One other issue that has apparently been going on for a while but was just recently brought to my attention. When started cold a makes a very loud clattering similar to a diesel car. I started it yesterday and heard this and thought it was gonna come apart. I shut it down right away. Started it back up after a few seconds and quiet as can be. just a slight tap like a little bit of loose valve lash. Hoping this will be adressed with timing belt replacement.
I'm still searching for a service manual and i'm not sure if removing the valve covers is part of the process or not, but was thinking it'd be a good idea any way to look for bent or broken vavles maybe?
One last note- has not thrown any codes.
Any advice and tips you guys can give are greatly appreciated. thanks in advance.

 

http://www.gates.com/common/download...ementGuide.pdf

 

Thanks for the link. Do you know if Gates is the OE supplier. Is it the brand they come with from the factory? Does anyone have any input on other items I should be addressing at this point?
Once again thanks in advance for your advice and input. Still learning here. It hasn't given us much trouble so I really haven't looked into maintenance items.