I know you are detailed and thorough, so no doubt you have checked the level and topped off as needed as the air worked out of the fluid (plus, the baster method should not have introduced any more air) but of course that has to be mentioned so it is not overlooked.
Do you still see signs of leaking (and you're sure it is p.s fluid that is leaking)?
I don't know how many times you basted out the reservoir and refilled for getting the ATF+4 back in, but it might be worth a shot to do it a couple more times to get the percentage up a little more (as you know, you asymptotically approach 100% but can never fully get there with the baster method). No promises, but if it were me, I'd do that just to rule that out as the problem before spending time or money on other possible causes (bad rack or pump - I know you replaced the pump, but most everything in aftermarket is suspect for these cars these days, and Auto Zone is definitely no exception to that.)
Only other suggestions would be to turn it lock to lock, and even briefly against the locks in case there's a stubborn pocket of air, and make sure the belt is tight. The belts need to be a bit tighter than some people think is good so they don't slip and cause vibration under different loading conditions. 1/4 to 3/8" deflection at mid span with moderate thumb pressure is best. (Belt not fluid contaminated or worn out?.)
So - the only things I can think of:
- still some air in fluid/fluid low?
- percentage of ATF+4 still not high enough?
- belt not tight enough?
- belt fluid-contaminated or otherwise needs replacing?
- bad rack or pump?
- still leaking/leak related to remaining symptom?
Last edited by peva; 02-23-2016 at 05:18 AM.