What I assume is a seperate problem, I've notice my power steering seems to oscilate between full power assist and lack of assist during tight turns- as I rotate the steering wheel through 360 degrees there seem to be tight spots at about 90 degree rotation and the wheel doesn't always return to center as you power out of a corner- requiring effort to straighten the car. This is a little freaky. I thought it sounded a bit like what you described. Any update on either of your issues?
I have been working on older FCVPI's for the past couple of years ('94, '96, '97 & '99/2K Franken-kluge) and every time I have encountered a 'hard steering' problem, it has been the universal joint on the steering shaft in the engine compartment. This is located up near the firewall, under the brake booster, right next to the driver-side exhaust manifold. On the '96, the u-joint was just 4 exposed balls that allow the joint to flex, which were rusted almost completely solid and caused problems at 90 degrees either left or right. I replaced this intermediate shaft w/ a new one from Ford (about $45, I think). The '99 had the same problem (almost impossible to turn after getting off the trailer from auction), but I found that Ford had changed over to a true u-joint like design w/ caps on an steel cross-piece. I was able to get this one working almost like new w/ WD-40.
To clean / replace it you have to remove the pinch bolt immediately below the joint (toward the gearbox) -and- the pinch bolt inside, under the dashboard. The inside pinch joint is usually clean, and light pressure w/ a small prybar or screwdriver breaks it free. The other one has always been more of a challenge, so I just leave it together and remove the pinch bolt at the steering gearbox (inside the plastic cover and away from the hot exhaust manifold). Be careful removing the cover (you will invariably break atleast one of the molded in clips / retainers) and match mark both parts before popping them apart, then pry against the gearbox while collapsing the sliding portion (up by the u-joint) until you have clearance to get it off the stud, then pull the whole thing out of the firewall. Don't turn the steering wheel or front tires until everything is back together, or you might have problems lining everything back up. You will probably find that the joint will flex on one axis, but not the other. Now, if you want, you can pop the other pinch joint using a vice and a drift. I used WD-40 to get the joint moving again, then blew out all the crude. I dripped oil back into the bearing caps, but I would have preferred AMSoil synthetic spray grease (all out). Finally, before reassembly I like to apply grease / antisieze compound to the stud and/or inside the pinch joints in case I ever need to get them apart again (I live in the Rustbelt around the Great Lakes). Also note where the groove is on each of the studs, because this is where the pinch opening needs to align so that the pinch bolt will slide through to engage the threads on the other side.
Re: the rough idle issue, I have read thru many older Service Bulletins that point toward vacuum leaks, fuel pressure problems, the IAC, and/or the DPFE, MAF and/or H02 sensors that might apply, though they almost always have related DTC's set. The problems that don't set codes (and many of the above problems) typically center around too much air and/or not enough fuel... One interesting SB discussed how to determine if a COP (coil-over-plug) was bad, or just the sparkplug, and it required an 'scope to resolve. Do you have access to a full function interactive OBD II code reader ? You probably need to look at real-time interactive values and determine a baseline -versus- problem occurance values. This would help you diagnose where the problem might be, and is something your Ford dealer should have already done (but I wouldn't count on it). Without codes, many dealership part-changers are as useful as a clutch pedal in an automatic transmission equipped vehicle. It's too bad they can't seem to keep real diagnostic mechanics around for long (or the one they have is too busy working on other things), but the business model rewards part-changers and penalizes time consuming diagnostic work.
Hope this helps ! !