Hmmm, try reducing the refrigerant 20%.
Buddy had same issues when he filled his newly converted R134 in his 3.2, we found reducing the refrigerant by 20% did the trick.
I use the ES12a in my R12 system, it works with R134 as well. Been using it for the past 5 years in my poopy oem system, still get complaints from wifey to turn the ac off
here come the flames...
Jim