i find it odd that both pothole switches were bad but if they were then that is one less component to deal with since you replaced them.
There is one other switch that affects the drive and that is the elevation switch at the base of the scissor arms. If that switch is bad and it thinks the scissor assy is elevated it will not drive fast.
Now depending on what type of control this unit has (bang bang or proportional) the pressure readings will differ. The service material gives you the factory pressure settings for main relief, steering, etc. You can get that off JLG's website if you haven't already.

Ok Did some Checking and found Two of the pothole switches are Bad Changed them out and still have the same problem. also pulled a pressure Reading and found low Pressure around 12 to 1500 psi. Replaced the pump and still have the same issue. Batteries Check Good and The motor is Good. Thanks

Ok Thanks I will check that out and let you know.

generally when you loose highspeed it is associated with safety switches like the pothole protection circuit that is used when the platform is elevated. I would check those first. There are switch(s) located in the pothole arm linkage and also at the base of the scissor arms that trigger when the platform is elevated to slow the lift travel down. If those check out ok then you will have to resort to checking hydraulic pressures down on the hydraulic control valve, one of those valves may be sticking. There are a couple valves that deal with fwd/rev travel, a dump valve and some other valves like a flow control valve and a check valve.
You can go to JLG's website and get the service book and it will guide you step by step through the process in the troubleshooting section. They are serial number specific so pay attention to that when looking it up.