hi 240 sages- have a misfire at sustained high speed. otherwise runs smooth and easy to start. 25 mpg around town. ignition wires and plugs clean and check out ok. cap and rotor new. coil is old and may be original. it is a bosch. old time garages used to have a coil tester machine but no more. dont want to get clipped at dealer or shyster mechanic shop. understand high speed misfire is often a symptom of worn coil which cant take the load of higher electrical output demand of 50mph+ driving. car is 92 245 in good condition with 220k miles. told by local wrenchers delco coil is just as good as bosch. delco is about $20 cheaper. appreciate your best advice on my diagnosis and whether to go with the delco coil.thanks tons oldduke