Problems with AC, WTH is going on??? Options

[conus00]

Long story short: As soon as I moved to Florida I lost my AC. Took her to the shop and found out that clutch on compressor was blown. After replacing the compressor and dryer (cost me $560) the car was fine for about two weeks, AC blowing icy-cold air. Yesterday I was driving down the street and out of sudden lost my AC again, on the top of it the car started jerking while under power.

The best way to explain it: when I'm driving with the AC on, it acts like it wants to go, then almost feels like bogging down (but without loosing any noticeable speed) and the speeds up again, resulting in noticeable jerk. This repeats in about 5 sec intervals. When I turn the AC off it completely disappears... WTH?
Also I noticed when I was slowing down to complete stop I hear this funny sound: sounds like "chit-chit-chit" and it speed variates with the speed of the vehicle... I remember the same sound shortly before I blew the clutch on the old compressor.

Can somebody explain to me what is happening?

I'm taking her back to the shop now, but would like to get second opinion.

Thanks.