Help with a diagnosis?

[Jgordon]

Hey, a little while back I reported a vibration in the shifter at 4300 RPM. that was this post:

Strange Happenings at 4300 RPM

In it, Chris suggested I try the following:

I think there was a note in the factory manual or maybe the Parts and Technical Reference that said something to the effect that vibration might be caused by the motor mounting. The solution is to park the car on level ground, loosen the 4 bolts on the the engine carrier (right by the fan) and then retighten. This releases any "twist".
-Chris

I'm going to attempt that this weekend, and I had another couple of points:

1. It happens in 2nd and 4th. I haven't seen 4300 RPM in 5th, but 1st and 3rd gears are fine. No problems. Since 2nd and 4th are roughly similar positions for the actual shifter, that led me to believe it might be a shift linkage problem, or something associated more with the shifter rather than the engine mounts.

2. It is somewhat intermittent, and sometimes goes away when the car is driven for a couple hours or more. Driving for a while isn't a surefire way to eliminate it, but it seems to occur less when the car is nice and warm like that.

I'm going to try to find the problem this weekend, but I wanted to ask you guys for some advice: Where to look, and what to look for? I know the problem is somewhat vague, so I'll try to clarify anything, if you think you might have an idea.

Thanks as always.

Jared

[Jgordon]

Any thoughts? Sorry for the bump, but I couldn't even find this on the BB, so I thought I'd put it back in rotation.