1992 Toyota Celica non standard AC problem

I have had an AC line with a very bad leak for about 2 years. I just lived without it. I tried fixing the leak by tightening the fittings and found out the hard way that they can’t be torked. I was in the process of changing over to 134. Anyway I have now replaced the lines and attempted to charge the system. It took a charge (2 cans of high mileage from a change over kit from Auto Zone) and gets fairly cool but it still cuts out randomly as if it doesn’t have enough 134. Also if I throttle up any the compressor cuts out and the AC light starts flashing. I have checked the pressure and tried adding more 134 but nothing seems to help. This may be normal but the pressure shoots way up when the clutch cuts out (I’m guessing this is just the pressure equalizing in the system). Prior to this leak I was hitting around 40 deg with R-12 without any problems except the occasional heater core freeze up easily corrected by bumping the temperature controller up a little.

Thanks,
David