furnace high limit switch measure 74-96 ohm, is it bad?
The limit switch should show a resistance of very near zero ohms when it is in the closed state. Sometimes your meter may show one or two ohms of resistance due to the meter leads if it has not been calibrated to null out the wire resistance. This would be more noticeable with a digital meter.

Make sure that you test the limit switch with the wiring removed from the switch. Sometimes if you try to measure a switch that is still connected into the circuit you may see an ohms reading that is above zero when the switch contacts are actually open. This reading coming from the attached circuitry. Under such condition you could incorrectly conclude that the switch was faulty by not noting the other state of the switch.