yeah whats the deal with them???

The big problem with K&N filters and toyota trucks is that the oil from the filter contaminates the Mass AirFlow sensor in the intake tube.  I see this EVERYDAY at the dealership where I work.  Either the customer over oils the filter, the oil gets sucked off the filter and onto the MAF sensor and then dirt that passes thru the filter sticks to the MAF and screws it all up  -OR- the customer NEVER cleans the damn filter because its a K&N and is supposed to be great.  The dirt then gets sucked thru the filter in mass quantities and fouls the MAF.

Point of my rambling?  Clean the MAF before you throw any more money at it.  To do this, be sure the key is OFF and unplug the harness from the MAF.  Remove the 2 little phillips head screws (and don't lose 'em- they're hard to replace...) and remove the MAF from the intake tube.  GENTLY spray the sensor off with some brake parts cleaner or carb cleaner.  all over the outside and down into the sensor on the little filament wires that are down in there.  The key here is GENTLY.  Then stand it up so the solvent can drain out. Wait about 5 minutes and look down in the sensor with a flashlight.  Still dirty?  Clean some more with a GENTLE spray then stand it up again to let the solvent drain/evaporate and wait another 5 minutes. 

IF it's all clean now, you can re-install the MAF and throw away your stupid K&N filter.  K&N's are great on the street- hell, I run one in my Supra.  But in a vehicle that sees dusty offroad conditions, it's hard to beat the factory filter in the factory airbox.  Your engine will thank you!

Hope this helps! 

Ryan