AC issues...again!!!

Well I'm back again scratching my head. In the last two years I've replaced my ac compressor three times, this last time I replaced the compressor, flushed all the lines, replaced the orfice tube, condensor, and accumulator. Installed 2lbs, 2oz of freon with an ACR2000, installed the correct amounts of oil into the system, pressures have been at factory specs, ac has been working great.....up until yesterday!!!! Last year I had to replace a leaking suction side shreder valve cause my ac was cycling off and on too much and wasn't cooling efficiently. I pulled a 45 minute vacuum @ 28in of vac. recharged the ac last summer and haven't had a problem till this week. Yesterday I pulled into a steak house after work to have dinner with co-workers. We were there for about an hour, the temp outside (Round Rock, Texas btw) was around 99-100 degrees. Car was alread @ operating temperature when we got back in to head home. Temp inside car said 141 on the thermometer in the ac vent, turned ac on high it dropped down to about 58 degrees, pulled out of the parking lot up to the stop sign to get on the freeway, ac compressor turned off for about 10 seconds, then turned back on, I took my foot off of the brake pedal and began to accelerate, ac compressor turned off for 10 seconds again, then back on, as I got onto the freeway it got cooler, droping down to about 42, then 38 degrees. Didn't do it again so far, haven't found any leaks yet. What could be the problem???? Also my compressor ONLY cylces if its on defrost, low, or medium-low. If I have it on medium-high, or high in never cylces, and the compressor doesn't turn off if I put my foot into the accelerator. If I want to pass someone I have to turn the compressor off. I've replaced the low-side pressure switch once, is there a high-side switch or are they the same switch?