Thanks guys I'm new to the forum and also to the thunderbird. NOt to good with the wrench so I appreciate all the comments being made. I really love the car and want to keep it. But it looks like I better not sell my spare.
The main point is that sometimes even the Ford service guys don't have access to the old service manuals anymore. I looked for someone who specialized in performance Fords and called 'em and asked a few questions. With knowledge you get from here you can start to discern if the shop really DOES know the car well enough to trust 'em with it. This was Ford's high-tech flagship in 1990 and they really are sweet when they're running right but there's lots of parts for them that are getting hard to find. Yeah keep your spare! I haven't gone one complete year without spending at least $500 and a couple of times over $2000. I bought it 6 years ago at 49,000mi for $5000, it was immaculate, but I've done plugs/wires twice, electronic shocks are $1200 installed, ABS is now like new, Cam Position sensor, belts, hoses, tires, transmission, battery, motor mounts, oilpan gasket (you have to lift the engine for that one), give me a few more minutes and I'll think of something else...oh yeah, it's time for new front rotors and pads. After that I think I may finally get a service free year out of her! I'll be into it for about $13,000 at 100,000mi, BUT I KNOW EXACTLY what I've got.
Also remember to take into account that the ABS and transmissions changed in '92 if I remember right so the year of your car is relevant in those categories when reading posts.
Finally if there's one name here whose posts I'll take to the bank it's Duffy Floyd. Dave Niebert and XR7Dave are really good also. Not to slight anybody else, I just remember finding stuff in their posts that helped me when I was learning about my car, which a is a '90 auto, mechanically identical to yours.