So my car started acting up on the highway lately. It started when I would cruise around 80mph for 10 minutes or more. The tach would drop quickly and the car would lose power for a half second at a time, but it just keeps doing it over and over everytime I'm on the highway. It feels like the car wants to stall or something. The power fades just for a split second, then it's back, then drops and so on.....it almost seems like fuel isn't getting to the engine or something.

My car is a 97 Z28 A4. Here are the issues I've addressed so far, thus ruling them out as possible problems.

New Plugs
New Wires
New Fuel Filter
Had my mechanic take it for a drive and he says that tranny is fine as far as he could tell.

Which makes me think that maybe it's the opti-spark, fuel pump, or my injectors have gone bad?
Any help would be greatly appreciated
Thanks in advance

Ben

 

Scan for codes

Check fuel pressure

Check to see if ICM is getting the right signal, should swing between 2-4 volts (try spacing ICM while your at it)

Test coil with multi meter believe it should be around 8000 ohms

If all that is good look at your opti

 

Check the fuel pressure while driving. You can temorarily tape a fuel pressure gauge to the windshield and have it connected to the schreader valve on the fuel rail. See what the fuel pressure does when the car "stumbles". Fuel pumps are a common failure on these cars.