I have the exact same car. I am still using R12 as R134 is not as efficient. The condenser (in front of radiator) is really limited in it's ability to dissapate the heat. Mine was also weak at idle and I also replaced the fan clutch as mine was weak after so many years. This helped some but still not good enough for the hot humid summers in slow moving traffic. I ended up designing a circuit (electrical engineer) to pull in the aux fans at idle only to increase air flow accross the condenser. This works much better. I think that the switch to R134 really hurt your AC performance. Good luck.