hi guys. not long ago i had a new clutch installed, and not long before that i had a complete tune. new leads, plugs, rotor, points etc the lot. dont get me wrong, my bug runs great, except for when trying to accelerate up slight hills on the freeway and such. especially after i have been driving for a while and the motor is hot, any acceleration to go faster than 100km/h or to try and maintain that speed up the slightest of hills, the motor pings and no speed increase.. is this normal? please help. i have a 1971 superbeetle.