Have to ask this one... Please
Good site. Has a section of tech articles for common problems.
Common problems for that style are dirty MAF sensor (easy), oil leaking through hardened valve seals on the right bank (involved but doable), clogged EGR passages (thought to be part of the valve seal problem), and of course, the air springs. I replaced mine with coil springs ($85), but there are online sources for rebuilt air system parts which'll cut your costs. Tech article for the labor. Dealers usually want $1200 and up for air spring rebuilds.
Look through the site, and use the search tool for "best model" or something. I recall threads which ID the best year(s) of that model. Panther Chassis forum is the one you want. I think the '97 was the last year of that body...and I recall the '95 or '96 was considered the best, due to engine/trans combo. But don't quote me, check the site.
Good car to restore. If you find one with all the above listed problems you'll get it for next to nothing, and they're all doable fixes. Put some Monroe Reflex shocks on it and you've got a good handling luxury car with V8 power that gets 23 mpg on 87 octane gas.
Remember there are 3 types of TC for those years, in order of luxury going up: Executive, Signature, Cartier.
Good Hunting!
Erik



