The boom pressure is good and the filter was replaced.  Any ideas?

What is the model?

If its just one section or some of them it might be moist in the remote controll. I had that once but its just a wild guess..

Bomerr, we need more info...what pump model?what year? any repairs on the hyd. System lately? Did the problem show up all of a sudden? Any problems with another hyd system on the pump?

When the energiser seals get weak and will cause it to lift slower at times 

hey Im also courious on this problem is it only one section or all the sections. is it when the oil is cold or hot. i found out when im haveing a problem with my pump think of all the conditions weather. rainy, damp, sunny, hot, cold, it helps when trying to figure out a random problem. 

34 x 1999 Sometimes it is the turn and the 3rd retracting, it seems to be when the oil is 50-70 degrees running mv22 oil

No hydralic pump problems but the boom movement has been slowing down over the last couple of years and the 3rd and turn started to move slower at times this summer 30 plus degrees.

I think you should increase the delta P on the boom regulator.

are your hand valves hitting the stops (or moving the entire distance the valve will go)?

Thats a pretty old ''secret brand'' pump

Seen more problems like that on severall old pumps and often the solution was to just change the whole valve block. Cheaper than looking for hours and hours for the problems and changing the parts bit by bit. But must admit Im not an expert on this stuff

Besides the delta P on the boom pump, check the pretension pressure on your handvalve, i am almost certain that will solve your problems

have you tried using the manual hand valves. when its acting up. maybe its a bad coil getting hot with use and starting to get weak 

Thanks for all the imput, i will check these things out.