Had a bad bad power / rough running problem and replaced the intake gasket. Fixed the problem.

Was told by mechanic (a relative and darn good, but not a Volvo specialist) that my AC compressor was bad and the clutch was sticking/grinding.

That was one week ago. Car is running good, except for:

some weird "bucks" or hesitations, especially under load.
AC cycles off too (this is a constant problem).
Terrible vibration of brakes, sudden onset...in last 10 days
Also, on way home today, smelled burning rubber. Doh!

Any of this related before I start prioritizing and fixing? It doesn't seem logically related, but then read something about power brake booster and surging. Also was wondering if my clutch on compressor stopped or caught, would this affect power via the serpentine belt? Dunno. Just asking people who know WAY more than me.

Thanks.