Car acts like it is fuel starved on full tank.

[sennafan]

My car acts like it is fuel starved, but it is doing it on a flat freeway. The car will keep moving, but the tach will dive to zero until the car kicks in again. I need to get it figured out so I don’t mess up my friend’s autox times. I have changed the computer, checked the battery ground. I am going to check all the grounds and the fuel pump wires. Any other suggestions.

[Sagaris]

Main DME relay going bad sounds like the easiest to check and most common cause for something like that.

[E30Gus]

Check your starter connections also. Depending on the year there is a spade type connector that can come loose and your car will die as you are describing.

[jlevie]

The tach taking a sudden big drop while the car is at speed says that the problem is electrical and not fuel related. The tach is driven by a data from the DME, so tach drops like that suggest that the DME is briefly shutting down, loosing timing reference data, or that the DME has an internal fault. Things to look at include the main relay, timing reference sensor(s), fusible link, DME, engine harness, or ignition switch.