So basically every issue with my car has been solved other than an irritating tendency to shake at idle.

The idle is at about 750, and when idling in the driveway or at a stoplight, the engine shakes slightly in the bay. From within the car, the stick shift shakes around a bit too. It isn't a violent shaking, but more of a gentle shaking in every direction (left, right, forward back). There is no pattern, and it disappears over about 1100rpm (although it could be that it is just not noticeable anymore, but still present.)

I'm sure my engine mounts are in poor shape, given that the engine torques itself slightly towards the passenger side if I apply the throttle from within the bay. But this is a definite shake, not normal engine operation.

I suspected timing first, but we rescanned the CAS not long ago and adjusted it perfectly. Mixture was screwed with before I got there, but I have calibrated it as per FSM. Idle set. BAC and Air Bypass Solenoid are both tested and functioning. Injectors rebuilt. Throttle body and UIM removed, cleaned, and reinstalled with fresh gaskets. Replaced all of the bad hoses on the rat's nest (a few were okay, so I gave them a thorough check and left them). All solenoids on rack functioning. Cleaned and tightened snorkel, filter, and AFM.

Suspect a vacuum leak, but can't find it for the life of me.

Is there anything else I should check?

 

Forgot to add:

Even compression on both rotors.

 

But what?
Fix the known bad things, like engine and probably trans mounts and then see what happens.
From your description one would assume the engine is actually running well, you don't list any normal symptoms of an engine related issue (hesitation, irregular idle, lack of power) and note no MIL, so why are you thinking vacuum leak instead of the most obvious and logical culprit?

 

I figured that the engine should not shake this much regardless of mounts, but if you're convinced that it's normal operation then I won't worry too much about the shaking. If I still have shaking after replacing the mounts, then I'll have to figure out if there's an actual problem.

 

Sorry, but I'm not "convinced" of anything, mounts are simply the first and most likely fix based on the provided info.

Consider it this way...
Vibration is caused by imbalance and in the case say of a broken fan blade, you'd expect the shaking to increase with rpm, not disappear as happens to you.
The rotary engine runs best at higher rpm, idle is simply that inconvenient state between being off and running correctly, so some movement is to be expected...which the mounts would deal with.
I used the Mazda competition mounts (still the rubber isolator style, not solid) and am happy with the NVH.

 

Sorry, didn't mean to put words in your mouth. Just saying I had thought it would be something else causing the shake.

 

And it may well be but since you've already cast suspicion on the mounts, that's where you start.

 

Not likely, but make sure the plug wires are running to the proper positions.