I here a noise under the engine when I am driving. It sounds like it is more towards the passenger side almost like if it were releasing air pressure. When hte noise goes off I can feel the car jolt and change the car's performance. I am not sure if it is a decrease or increase in power becasue as soon as the revs go down I accelerate and the power feels stronger. I have never heard this before, but then again I just got the CV Joints replaced along with all my engine gaskets.

Any suggestions as to what this might be?

A/C compressor clutch kicking in and out.

Check the Alternator idler pulley.. The bearings are known to go causing a growling type noise..

Gl..

I will look at it but is it something relatively easy to fix and what are the symptoms.

Get a long Screwdriver and on the front of the Engine. There is a idler pulley right in the center. Take the screwdriver and put it on the 14mm nut on the front of the pulley , and see if you hear it humming through the screwdriver by putting your ear to it. It's common for those pulley bearing to go. Gl..