Testing at just two locations will tell you a lot. Since the lines going to each lift and tilt cylinders are Tee'd together, all you need to do is put a gauge on the lines going to both ends of one of them either at the same time or seperately. With a gauge tee'd into one of the lines move the cylinder to the end of it's stroke and read the max pressure. Then put the gauge on the other end and take the cylinder to the other end of it's stroke and read that pressure. That will tell you whether the pressure the pump is making is the same on both circuits.
If the pressure is higher on the lift circuit than the tilt circuit, or different between the ends of the cylinder on the same circuit, that will help you pinpoint the problem. Now if its the same (low) on both ends of both cylinders then you could have either a bad pump or the main/system relief could be stuck open/damaged and dumping the pressure . Unfortunately the only way to test for that problem is to tap into the main line going into the valve and put a load on the system like I talked about before.
All you really need to do is put a load on the system and the actual flow rate isn't an issue, all you need is a Tee with a needle valve on the outlet/downstream side of the tee to give you the load capability. Slowly closing the valve should cause an increase in pressure. All you need to do is slowly close it and watch to see if the pressure reaches the spec. If it stops rising before you get there you know the pump is bad, if it continues to increase as you close the valve a little more then all is OK with the pump and it has to be the main relief valve.
If you want to get yourself an assortment of fittings and gauges to check this problem, and to have for future use, give Surplus Center a look. They are about the cheapest place I know of to get pretty much everything you might need to tap into and check the system.
Once you get everything checked out, like I said, shoot me an email, or post back and I'll be glad to offer up any assistance I can. Wayne