At what mileage should a timming chain be replaced?

Yes it does, but I don't believe there is a scheduled mileage set by the manufacturer for replacement.

It sounds like the timing chain was replaced one tooth off. The only other option if the timing chain is correct would be to adjust the ignition timing. Since the timing chain was replaced I would think it to be the first problem.

remove the valve cover and have someone crank it over seen more crank sensors go bad then chains but i don't know your mileage

1st of all be sure to read the manufacturers information under your hood about the procedure of adjusting the timing on your jeep, afterwards, you will need a timing light to do this procedure, and if the adjustment of the timing doesn't want to stay in place, after it is set, then it could be your timing chain has an a certain amount of slack in it due to wear, 1st of all how many miles is on the jeep, if it is very high mileage, this could be the problem causing the slack, and the timing not staying in it's proper setting. if this is your problem, then the timing chain will have to be replaced.

Not sure but I think your car has a timming belt.I think they should be replaced around 60,000 miles

it has a belt.recommended replacement interval is 105,000.if mileage is lower than this i personally rec replacement at no more than ten years.if it hasnt been replaced do it.i assure you when it does fail invariably it is always at the most inopportune time.

This year uses a timing belt and it should be replaced every 60,000 miles, this is very important to have the belt replaced at the recommended mileage, the engine is not free wheeling and if the belt breaks you can bend the engine valves

you will probably find that a timing chain is in the engine for the life of the engine or until it needs to be replaced,

At 75 000.

The timing chain on the Trailblazer 4.2 L is a metal chain. Unlike plastic timing belts that require replacement at certain mileage, this metal chain should be good for the life of the engine.