Hello guys and gals! I am hoping I am posting this in the correct section. If I do something out of place please let me know and I will be happy to adjust (new to the sight). I appreciate any and all thoughts and have read through many of the posts already.

A belt is going bad (not sure if it is the timing belt-can't remember) and the mechanic that has worked on this hummer for me and the previous owner has quoted me $2200 parts/labors. He says there is no prediction of when it will go out. This was about six months ago. The mechanic also threw it out there for me to consider putting in a new motor ($4800) due to the mileage (245,000). I work in healthcare and do a lot of travelling for my job. There are a few other issues such as I have an oil leak and am adding 1 quart of oil 1-2 times monthly. recently, my hummer has started stalling at stops/red lights unless I am able to give it a little gas or come to a complete stop rather than a slower rolling stop. Due to this new issue, I need to make the decision on fixing the belt or putting in a new motor as soon as I can. I have talked to a couple of people who suggested getting a new car. I do not want to put money toward a new car if I can keep my hummer. I love my hummer and want to keep up the maintenance as long as I can afford to. I am appreciative of and hopeful for any advice. Thanks in advance!

 

Forgot to say My hummer is a 2006 H3

 

245,000 miles? New motor, not a used new to you motor.
Even if you tear down the engine to put a new timing chain and tensioner in it, fix the leaks and stumbling issues you will still have a motor with 245,000 miles that will STILL consume 1 quart of oil 1-2 times monthly!
I think you kind of answered your own question with reliability being a concern "do a lot of travelling for my job".

 

There is no timing belt on an 3.5L H3 motor. Timing chain, yes. Balance Chain, yes.

Its stalling at lights because you have not performed simple maintenance, like cleaning your MAF with MAF cleaner, cleaning your Throttle Body with TB Cleaner, etc....
See the list of items you need to do here. Acts like it wants to stall/rough idle -No CEL -What To Do:

 

Thank you so much for your help Tainter and Old Docs! Would you suggest looking for a motor myself or letting J (mechanic) order it? Are you aware of any type of upgrades to this motor that would save me some gas or be helpful to my hummer? If you have any resourceful websites I can read about, I don't mind doing as much reading as I need to to get myself educated about this. I am good at a lot of things, but mechanics is definitely not one of them I do appreciate your time and help!!