2002 V70 XC AWD Poor running, rookie, Denver thread

[rookiemechanic]

Happy new year everyone!
I am in need of a little suggestion and advice here. The mechanic is telling me that the only thing left to do to cure the reduced engine performance problem is to open the flywheel/drive-plate and look for anything out of ordinary and replace it with a good one. For that, since he has to take the transmission out, he is going to charge me $1000. Though he told me that he won't charge me if he does not fix the problem but how do I even know if that is the problem in the first place and it is going to fix it. I am just skeptical about the whole thing and want to think it through before I keep putting my money for repairs that has not helped me at all so far. I have spend upwards of $3500 in repairs and other things so far for a car I bought for $1800. So, at this point I am thinking if it is even worth it and say goodbye to this mechanic. I am worried about the problem coming up after few weeks of driving and when I go back to him I am afraid that he might tell me the problem is from something else that happened after the repair. So here I am, quite uncomfortable to pay $1000 to just diagnose a problem which may or may not even fix the problem. Any suggestion here will help me think clear and take rational decisions. What if I just drive the car with the reduced engine performance message for few months? Is it going to do any additional damage to the car, like damage to the motor or the transmission?
I just need to buy sometime and see if this is that much of a serious issue after driving for few weeks. Also, now I am thinking of getting a second opinion. The downside of going to a new mechanic I think is that he won't be as familiar with the car as my old mechanic is and he will have to spend few hours in diagnosing the actual source of the problem. I will be in loss if he points to the same source (drive-plate/flywheel). If there is a way I can find out for myself if the drive-plate is wearing out or not then that will give me a reference point. I am not sure if that's even possible without taking the whole thing out. I am pretty undecisive at this point.
There's is a pretty good volvo mechanic in denver, Bob's Volvo, where I am thinking of taking the car next. If anyone here knows the mechanic then please let me know. Any suggestions and insights on my state will be greatly appreciated. many thanks!

I just want my car to drive fine to the mountains so that I can snowboard!

[abscate]

Split other poor running thread from this one...let us know how this worked outM