Rpm gauge jumping all over

I have a 94 ford Taurus SHO and while I’m driving my rpm gauge jumps all over the place, when I’m stopped it drops down so low it seems as my car will die. what could be the cause of this and is it terribly expensive to fix?

From this distance, nobody can properly diagnose this problem. If the “RPM gauge”–actually the tachometer–is jumping all over the place, that could indicate a problem with the engine or with the transmission. Does it seem that the transmission is slipping? In other words, do you observe high RPMs and hear a lot of engine noise, while the car is accelerating slower than usual? If the transmission is not slipping, then the problem probably lies in the engine.

If the car is not up to date with maintenance, I would begin with replacing anything–plugs, plug wires, air filter, fuel filter–that is overdue for service. If the problem persists, then you might want to look to the Mass Air Flow Sensor (MAF) for the source of the problem.

However, as a first step, I would strongly recommend getting the stored trouble codes read. The only problem is that this car is so old (and has the outmoded OBD I system) that some garages will be unable to interpret those codes. Make some calls to find a garage that is able to interpret OBD I codes, and that should lead them to the source of the problem.

When the tachometer is jumping around, does the engine power feel uneven? Is the Check Engine Light ‘on’?

yes, it was also suggested to me that I might have an air flow problem, sensor or exhaust blockage.

If your check engine light is on, you need to have the stored trouble codes read. Some parts stores do that for free, but might not be able to diagnose your car because I believe it uses the older On Board Diagnostics spec (referred to as OBD-I). You may have to take it to the dealer for diagnosis.

Once you know the part causing or signaling a problem, it’ll be a lot easier to fix.

Please describe if the engine power jumps around with the rpm gauge jumping around. And, you could answer the other questions you have been asked, in order for anyone to be able to help you.

My engine power seems to jump around with the rpm gauge causing my car to shimmy or surge at times. My check engine light pops on but not all the time while that is happening. I’ve basic care maintenance, air filter, spark plugs, oil change and all of that taken care of. I will work on taking it in the have codes read.