If you are going to get a manual then I would strongly suggest a genuine manual from GM since they put every little thing in the manual. I bought a chilton then a clymer manual and believe me, they're crap!! Haynes do make somewhat better manuals though.
Oh and I own an 85 Citation and yes I have seen all of those manuals.
I have a 88 celebrity that did the same thing. It went a whole summer dying every time I was in town. It would run perfect until it got hot and when I shut it off it would not idle on its own until it cooled down. Sometimes I could turn off the ignition and would work. The winter went without problems and this summer was the same. My mechanic could never figure what was doing it, but seemed to fix it self.
Unplug that solenoid and call some transmission shops. Replacing the THM125C's TCC solenoid on cars I have owned and friends have owned has cost anywhere from $150 to $600. CALL AROUND. Some shops are more experienced with the TCC solenoid and are willing to cut you a deal if you bring it in when they have time to do it.
The lockup solenoid on these cars only costs about $25!! Save yourself some money and learn how to fix it yourself, there are tons of places on the web that tell you how to do it and have pictures. I did it and it only took me about 2 hours total work time, with fluid, filter, gasket and the part total spent was about $60. That's a lot better than $150 to $600. The only other major problem I have had in 210K miles is the timing gear replacement, which entails removing the engine, so that was about $700. Not too bad for 6 years of reliable service from this vehicle.