Power trim/tilt problem 1990 140hp V4

I am experiencing problems with the p/trim system (conventional) on a 1990 Johnson 140hp V4 looper. After having done a full repair on the engine we mounted the p/t unit on its base and powered the unit 'til the tilt piston was in the proper position. When we powered the unit down the trim pistons were the first to retract (uneven), after they were fully seated the tilt piston started to lower but all of the sudden it went down as if no pressure. Then it wouldn't come up. Mechanic checked for air in the system, worked the manual release valve and replenished the unit but did the same thing. We took the unit to a shop, replaced seals, o-rings and replenished the hydraulic reservoir. The mechanic powered the unit and operated well up and down. We installed the unit back and did the same thing as before. After three more attempts and a new electrical motor installed we decided to quit. The fact that the trim pistons are retracting first when the tilt piston is extended makes me think that something is not working properly or is it? Any suggestions?

"The fact that the trim pistons are retracting first when the tilt piston is extended makes me think that something is not working properly or is it? Any suggestions?"
The answer to this is yes this is normal operation, my working unit does this all the time.
In regards to your issue you have a sticking valve, You can purchase a use replacement unit or buy the kit and service the existing one.
Issue like this can happen if the unit was leaking prior to this and water was present in the oil. Water and fluid does not mix well it causes the seals to expand and crack ...

i'm not sure,i understand,the full prob,.....but,...w/no load,the trim WILL/can and most times DO etract first....pls explain ur main prob,as i am way to lazy....to re-read all that....maybe,..i can help..:>)

NTBRAN thanks for your advice!!! Will consider options.

jwb: Thank u for reading my post. In simple words, when unit is in UP position and you power DOWN, the trim rods will retract first (after completely seated) the tilt rod will start moving but will "bleed down" as if no pressure in the tilt cyl.