In terms of the misfire are there any specific details? Is the misfire all the time? Or does it misfire at certain points, ie idle when hot, etc?
Think mike1967 is pointing towards valve seat issues, etc. Certainly this could be the case, equally I would suggest starting with the low cost stuff if you haven't already, Typically these cars misfire due to coil packs and plugs failing, which are cheap fixes in many cases, if these have been checked out then move on to compression test, could do that before coils and plugs. Basically a misfire will happen when the offending cylinder(s) is missing fuel+air mix, compression, spark or there is a timing issue. You can diagnose most of these by a process of elimination i.e., swap plugs and coils from another cylinder and if the misfire moves then its either the plug or coil, compare compression on cylinder 1 with the other cylinders - they should be within 14 psi. A more comprehensive compression test is the leak down test (read up) which will indicate if the compression is being lost through rings or valves and finally the dynamic compression test which will indicate a fault in valve seating when under load/temperature. Spark timing is fixed, which leaves VVT, which requires accurate alignment of the cams with the crank. Have you tried disconnecting one of the cam sensors - if you do, does the misfire stop? Disconnecting a cam sensor disables the VVT, forces the valves to do full lift and can indicate a timing issue or valve seat issue. These engines drop valve seats which can be very expensive to fix if it happens when the car is being used.