Shaking & Vibration at idle worse in reverse goes away when driving more than 5mph. Sounds like vacuum leak. Heard about a rear motor mount control solenoid or air intake could be CULPRIT???

 

Often, but necessarily only. Yes, motor mounts. I would say if you can, do all the motor mounts at this point. The rear is the most difficult. About to do this myself. Rough at idle, smooths out on moving. I can see the front mount is completely cracked and I presume the rear is quite dead.

One of things that can help confirm is to 1 - Open hood of car. 2 - Have someone stand there looking at engine 3- Have someone else put foot on brake and car running, then shift it into drive, back to park, then reverse. The person watching should see the engine "lurch" forward or backward which shows the motor mounts are broken or otherwise dead and in need of replacement.

It would probably be the first thing I would change on an older car today as this is common for cars of this mileage and age if it has not been done yet.