Sounds like a little maintenance needs to be done here. I would advise you to get your SHO fixed, even if it is a large sum of money. I say this for 2 main reasons. 1: The car has considerably low miles for the year, and 2, I have read in several auto magazines that the SHO will be a future collectible car.
I own 2 SHO's. One 1991 MTX and one 1995 ATX. I have owned the 91 from day one straight off the lot and have had all the required maintenance to it (60k, replaced water pump, etc...) And to this day it has been very reliable and still holds its impressive power.
All I'm saying is to get your SHO fixed and as long as you do all the basic and required maintenance for this car, you will have a very reliable fun car, and will have to put more and more money into things that could have been prevented.