A few more questions for you ;-)
Have you tried softproofing ?
What do the softproofs look like ?
Do you select paper white simulation ?
When was your monitor profiled, they need to be done every month or so ?
Which rendering intent are you using and have you tried others.
Have you run a nozzle check on the 4000 ?
Lastly, has the problem just cropped up, did you change anything (like a printer cartridge )