07 ford F150 5.4L 3v trouble codes

Hi everyone I'm working on a friend of mines 07 f150 5.4L 3v, it's running really rough pulled codes which are - P0305, P0022, P0420, P2198, P0171, I changed Plugs, air filter and oil & filter about 2 months. I switched the cop and plug to a different cylinder no change I did clear the codes all that came back was P0022 and P0305 so I'm thinking it's the vct solenoid causing the misfire, is there a way to test the vct solenoid?

I had one that the internal screen blew out and jammed the solenoid rod so that it would not move. Before I saw that, I was going to swap the left for right and see if the codes changed. I didn't come across a easy way to test. You might want to try http://www.ford-trucks.com/forums/forum24/
or
http://www.f150forum.com/f4/

Well I took the valve covers off removed the vct solenoids to me they look good no sludge or screens blown out so I think I'll change them anyways just to be on the safe side. Is there anything else that would cause a code P0022, timing chain ,tensioner or lifters?

Well I changed both vct solenoids Trucks running good no misfires or codes just goes to show you the they my look good but there's internal problems in the vct solenoids. Job took around 6 hours start to finish.

Thanks 65comet for your help, by the way some people say you have to remove the right motor mount to remove the valve cover but you Don't have to, all you have to do is remove the tranny dip stix bolt and the A/C accumulator bracket should give you enough room to remove the valve cover. Thanks again