8 weeks ago my 2003 Miata with 80000 km on the clock started running lumpily so I took it to my local dealer. They diagnosed the need for a new ignition coil and leads [at a replacement cost of CAD$800] which were on back order from Japan. 8 weeks later, and the summer gone. there is no sign of any parts. I see aftermarket parts available on the internet at a reasonable price. Should I order and replace myself? I am mechanically handy.