02 sl1 misfires 58k miles

[veedubmechanic]

So worked on a friends car today, scanned and found p0301 (cyl 1 misfire) and p0507 (idle control too high)

Had original plugs and wires on so I swapped them out to some fresh ones and ran a little bet better but still gets same codes. I replaced the air filter and found the throttle body little gummed up so cleaned it up with some throttle cleaner.
I know vw's have lots of problems with coilpacks cracking and misfires and the gm one looks more open and able to arc. Didnt have any water to mist on but my question is do gm's have lots of problems with coilpacks and arcing? It seems to rev up fine and run at 3k rpms ok but when i let off it puts a little and idles at 1500rpm.. Temp guage seems to be ok.