Just brought my car out from IL. All forged 408, about 520 rwhp w/o the spray. It has a walbro 255 pump in it.

So today I was driving the car and got on it 4th gear around 1500rpm, by 2000 rpm it was stuttering and felt like it was starving for fuel. I tried other gears, 1st didn't really do it, took it to about 5k and didn't want to go past, same for 2nd....but 3rd and up will start "stuttering" under full throttle from about 2000rpm and up. It really feels feels like it's starving for fuel.

First thing that came to mind was the fuel pump. But what a friend brought to my attention was maybe it's the gas. The car has been in cali for maybe 3 weeks. My fuel guage doesn't work so I've been in the habit of filling up often. I've probably been to the pump 4-5 times out here but only put in 4 gallons at a time, so I haven't completely emptied the tank of the 93 octane from chicago but obviously there's been getting less and less. Best I can do normally out here is 91 octane, and I hear it has alot of additives. I noticed more carbon coming out of the exhaust since I've been here too. I'm pretty sure the last time she was tuned it was set for IL gas (93) being I planned on having it there. Does this sound like it could be a gas and non fuel pump related issue?

If it may be gas related would a bottle of octane booster with a tank of gas cure this issue?

 

If you don't want to take it to a reputable tuner to verify the tune for your fuel and elevation, put some Torco octane booster in the tank. If the problem disappears, it's your octane. If not, it's something else. Either way, you might end up at a tuner to fix it. Just in case I have to say this: don't take it to some generic shop or the dealer.

 

Why doesn't the fuel gauge work?

Just learn how to go into the codes on the Driver Information Center (DIC) and write down all the codes and then clear them and your gauge will probably work again. Fill up with gas plus a bottle of Chevron/Techron and it should clear up the gauge problem after a couple tanks....