kent,
try checking the control valve
the following problems can cause this symptom
- valve spool springs are weak or broken
- internal control valve leakage (worn spools)
- load check valves defective
- leakage of cylinder lines or piston seals
- trash in the control valve

one of these things could be causing your leak down of the lift and tilt
pull the valve and check the neutral return springs and make sure they are not broken, generally if this is the case the lever will be very mushy and will not have that 'neutral detent' centering when you let go of it. Also remove the check valves and relief valve and make sure there are no broken springs in those. check for any debris while checking these.
If you find no issues from the above checks then you may have a cylinder packing problem causing leakdown.

good luck