83 Digital Tach display
 

My 83 non-turbo 280ZX is just about running as good as ever except for a weird tach display when above 2500 rpm's. At 2600 rpms the tach displays normal rpm's via the gauge lines but in addition I get flickering tach lines that are displayed at the top of the tach gauge. Bad display or ???
Not sure if it's related but occasionally at high RPMs with hard acceleration the car's response is sluggish and then takes off almost like not getting fuel or enough air? Idle is just a bit rough with an occasional miss. All in all hard to complain for over 30 years and gas mileage is still around 25.
Appreciate any guidance, thank you.
Sgonzo

generally good advice that will save headaches down the road. :
Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion. DON'T USE DIELECTRIC GREASE.

Replace outer tie rod ends, and ball joints. replace the bushings with poly (don't forget to lube them as directed unless you like squeaky things). New shocks. Get new boots for power steering. all those things will make you think you are driving a different car. doing them piece meal is a waste you won't see a great improvement until you do the complete job. You need to get the car realigned after messing with the front. Have your tires in good shape and rebalance. Rear bushings nice too but more work and you won't notice as great an improvement. Rear shocks also because if the fronts are gone so are the rears. if car squats when you jump on the gas the rears are gone. If you have the electro adjustable shocks they are DEFINITELY GONE.

Time to swap to analog gauges!!