Engine Performance problem
1996 Infiniti G20 4 cyl Front Wheel Drive Automatic 104000 miles
Tach is jumping erratically. Will drop to zero and jump up to max and will continue. Does not happen at first start but after about 5- 10 minutes of driving. Do not notice any other signs and seems to run fine except for the jumping tach. Plan to do a full tune-up. Any other suggestions for this fix? Tach is now not working at all.