How difficult to replace timing chain -2.7?

My wife bought a 99 Intrepid over the winter after her Neon was totalled, and it runs OK, with only an occasional puff of smoke under acceleration at times. It has 103,000 miles on it and we have no idea what was done to it prior. I have made sure all maintainance was brought up to date and switched to synthetic oil to keep it going. I have heard a lot of horror stories on the 2.7 and most seem to involve the timing chain causing massive damage when failing. Also I have heard you need to replace the chain every 100K, and since I have no way to know if this has been done before I want to do it or have it done sometime in the future, when I can afford it. I just bought a service manual for it, but having never done this before, I need some input. Is it better to have a shop do this, or, is it something I can do at home? Any ideas on cost involved either way? Looks like a complicated motor.

it is not a nice job make sure the engine is not full of sludge before doing this job

it's not that bad the new timing chain has gold color links where the marks line up so just conect the dots so to speak