Thank you! I sure have, no improvement after jumping the EGR computer. I have also checked the OVP fuse, the diagnostic port on the driver’s side fender, the two pin connector on the passenger side firewall (which I understand to be tach related) and all looks good with good connections. It seems somebody tried to fix this at some point in the past, because I have one of the green PCB tach amps attached to the diagnostic port and several capacitors replaced in the dash. I do also have several, maybe 5 or 6, various electrical connectors under the hood that have been disconnected by a previous owner, I believe during a shoddy attempt to delete/disable the EGR. I’m wondering if any of them are related to the tach.

I am going to replace the capacitors in the clock while I have the gauges out anyway, since they’re the wrong values. Any chance you know the correct value for the one in the tach, or do you know where I might find a diagram of the circuit?