If you buy a new chain from mitsubishi, you will see the updated chain - its physically different and stronger than the original, same with the tensioner.
btw - if you want your mechanics to use torque wrenches then why not buy one yourself and make them use it, Mitsubishi have pretty nice torque ranges in their manuals and allow for quick work - e.g. the timing case smaller bolts are torqued the same - so set once and click away.
btw - your chain is not on correct marks - a mitsubishi dealership here in Houston showed me the 4B10 service literature on a screen which is similar to the 4B11 literature for the timing chain. The dot sits on a chain link, not between chain links like in your picture. (this is what I mentioned when I said that a worn chain allows you to seat the chain wrong while it fools mechanic that its correct).
anyway - find true TDC of cyl1 - either by screwdriver/rod/teeli or smokey yunicks method or precision method with dialgauge. (Ive been using smokey's method since I was a lad in Pakistan - its precise and cheap)
Then check the camshaft timing marks to exact dead zero TDC of crank - make sure all spark plugs are out when you are doing this so you are not fighting compression. You will have to use a camera to take a picture from the back of thee engine to check the camlobe angles of cyl1 to see the mistime correctly.
If everything is good, then you need to dig deeper on why the engine is faltering.