94 - several of problems - all vacuum related?

Having some problems with a 94 Explorer:

1. Rear of valve cover, driver side, several vacuum hoses controlling ???
Intermittently, one or two will blow off when starting the car, resulting
in rough idle, etc. Put them back on, car runs fine till the next time
(weeks between).

2. "Pinging" which seems to be getting worse and doesn't improve with a
better grade of gas. Vacuum advance?

3. Transmission now going to very high RPM before switching gears. Using
the shift lever results in good changes, so I'm thinking the tranny is OK?

These seem like they might share a root cause - some sort of vacuum
problem. Any ideas of how to troubleshoot? I can't afford to pay myself,
let alone a mechanic, unless it's absolutely necessary.

Thanks

tweaks