Fuel gauge jumps back and forth with rough idle!

[flyfishing]

My daily driver stage 3 has been faithful for many years. 3 weeks ago, I started noticing rough idle on cold start. It would rev up and down and sometimes seem like it wanted to die and it would be rough for maybe 20 seconds and then all is good. Eventually, it threw CEL and I just haven't had time to take it to the shop until next week.

Anyhow, I would clear CEL (b/c I hate to see the orange light) and eventually the rough idle would occur all the time on cold start and CEL would come on. I noticed that my car smells much more gassy now. Today and I should have made a cool video, the fuel gauge jumped from empty to 1/2 full (which it was) and back and forth for like a minute. I drove my car home for lunch and parked it and took my other car (v10 m5 to work).

Has anyone seen this issue before? I am taking it to shop next Friday. Car works great once it gets past cold start. Codes show that is P300 which is intermittent misfire. I've had spark plugs and new coil packs replaced about 2 years ago. I am thinking there is an issue with some fuel regulator that causes the car to get too much or incorrect mixture of fuel and misfire. Or maybe my MAF is dying.

[erykv1]

when was the last time you changed the fuel filter? what pump are you running?

[flyfishing]

I don't think I have EVER changed the fuel filter. I use 93 octane (usually Shell or Exxon).

[vavJETTAw36]

weird the gas gauge should be completely unrelated to the other issues as it's just a float sensor. If you are smelling gas... Have you checked fuel pressure? Id check the pressure first before changing the filter. If it's getting good pressure don't waste your time on the filter.


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