Oh...My...God...I am such an idiot. Were he alive today, Herr Porsche would confiscate my car on the grounds that dumkoffs should not be allowed to drive his vehicles. This is really unbelievably dumb...it is hard to even type the words because I am so unbelievably embarrased...but here goes...
Not realizing that moving the shift lever to the left turns the shift linkage to the RIGHT, I had set the shift linkage adustment way too far to the right. So the gears were all shifted to the left. What this means is that when I said the car seemed like it was in third when it was in first, it really WAS in third (no wonder it had no power). When I thought I was in third, I was really in fifth. And when I was trying to shift into fourth, well...I was actually trying to shift into reverse at speed. And when I thought I was shifing into fifth, I really was in fifth except I was pushing the lever way to far to the right to do it. I am so glad I caught that mistake before completely destroying my transmission...
Anyway, if my Pelican membership doesn't get revoked for that bonehead move, I can happily report that re-adjusting the shift linkage fixed most of the problems. I also re-adjusted the clutch linkage. So now the car shifts smoothly through all five gears. No whining or whirring or grinding. And yes, the new 7:31 ratio seems to give it a big boost on the butt dyno (now that I am actually using the proper gears). So for the first time since April, the car is once again a five speed. Hurrah !!
However, the chattering sound remains. It seems to have no effect on performance, so part of me thinks I should just buy ear plugs. But all kidding aside, it only happens when the car is in motion, seems unaffected by engaging or releasing the clutch, seems to go away when I am in fifth gear (not third gear as previously reported), seems unaffected by my speed...it isn't rythmic...almost random...I am, of course, very suspicious of everything I touched...fifth gear slider and reverse idler arm seem likely suspects (hmmm...)...CV joints (maybe poorly torqued bolts, dirt, bearings "messed up" somehow)...sway bar mount...heck maybe I left a wrench inside the tranny before I closed it up...
Very weird.