ford 3400 (3000) 3 point hitch jerky/slow after rebuild

Hi, I've used the forum for information a lot before, but just registered and this is my first time posting. Lots of great information shared here and I appreciate all the info I've gotten.

I recently did a bunch of work on the rear end hydraulics of my ford 3400 (3000 rear end as i understand it) and, while many problems were fixed, the three point hitch is acting erratically (more detail below) and with winter fast approaching I'm worried it is going to fail on me in a foot of snow if I ignore the problem now. Looking to get advice on what might be causing this problem, and how I can fix it (or if I shouldn't worry).

Background:
- I've owned the tractor for the last three years and the 3ph has always worked fine with the exception of not holding position control (already solved)

- I recently had to split the tractor at the rear housing/transmission junction and while I was in there did a full lift cover overhaul as per the service manual. This included new o-rings/gaskets on all parts of the lift cover, hydraulic intake/return manifold, new return filter, cleaned the suction filter, adjusted all linkage in accordance with the manual. Also did the overhaul on the flow control system.

- When I got the tractor back together everything worked, but the 3ph was very slow. Ran it for a few days and realized I still had the flow control valve turned completely all the way out from one of the checks I had to make during reassembly. Turned the flow control back in and it seemed to work better but as I was testing it, it started acting really erratic: a couple times it wouldn't lift for 10 seconds, then would lift some very slowly and pause, lift etc. Sometimes it would lift steadily, but would take a full 10 seconds to get from ground to full height.

Things I have already checked:
- removed allen plug on pump to make sure it is primed, shot a ton of fluid out so I'm guessing it is good.
- Hydraulic fluid is full (double checked after priming)
- Fluid is correct spec (universal hyd/trans tractor supply)
- No visible damage to suction/return lines outside housing, but haven't had them off tractor

Other possibly relevant info:
- very small seeping leak from accessory cover on top of lift cover (where you attach a remote)
- no visible leaks anywhere else
- a minor but persistent rear end leak (what I split the tractor to fix) over the last year may have caused the pump to have run without fluid for very brief periods (2-3 minutes before I realized I couldn't lift the 3ph on two occasions) on only one occasion did the pump have to be re-primed due to the fluid level dropping too low. Could pump be dying?
- 3ph is currently lifting and holding a ~1000lb rear blade (weight has been added to it)
- fastest it will lift this blade is about 8 seconds, and it's taken up to 20.

Apologies for the long post, wanted to provide all the info I could, thanks for reading if you got this far.

Source: http://www.tractorbynet.com/forums/new-holland-owning-operating/263708-ford-3400-3000-3-point.html

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