ATF Overfilled?
So to preface, I'm not entirely sure that I know what's going on with my 98 LTD (3rd Gen). The interwebs seem to refer to the issue as "rumble strip", and that seems to describe the issue pretty well.
So some backstory: ever since spring, when I installed a K/N CAI, after or during a heavy rain I get a "rumbly" sensation at ~1500-ish RPM. This has largely subsided, but still occurs now and then. My searches pertaining to this issue turn up things like "leaking vacuum hose", but I'm fairly confident that this was not the case. I thought it was something more like water rushing behind the passenger-side headlight and getting sucked up by the CAI.
On my way to VA a couple of months ago, I checked the ATF while pumping fuel, and it seemed a little on the low side. When I reached Heathsville, I topped 'er off, and everything seemed fine until I got back to Knoxville five weeks later. I also took two trips to D.C. during this five-week period with no issue (unless it was raining heavily, in which case, see above).
Back to the present: the "rumble strip" phenomenon seems to occur in third gear, but it's sporadic. Some days it doesn't happen at all, others, it happens constantly. So I checked the ATF, and it appears high (at the lower "hot" mark after sitting overnight). I'm not sure what to do about this. I suppose I could withdraw some ATF to get it closer to the perfect volume and eliminate that vairable, but I'm worried that I may be beginning to lose 3rd gear.
So that's what I'm doing to my 3rd gen today....troubleshooting. lol