Are those the ONLY error codes you get: misfire cyls. 3, 4, 5, 6 & 8? Unlikely to be 5 out of 8 coil packs failing at the same time, I'd say, but I suppose not impossible. Likewise spark plugs. If really no other fault codes I'd start with the cheap, easy stuff: crankshaft position sensor, mass airflow meter, spark plugs, coil packs -- in that order. Sadly without any other error codes it could be very difficult to crack.