[Ron56]

I have an 07 V6 with a C&L intake/93 octane race tune (self-installed in July), Screamin' Demon wires and coil (installed by garage in July), and FRPP cat-back exhaust (a year old). My problem is that when I'm driving in the 1000 -1500 RPM range for a while (in traffic, for instance), then accelerate, the car hesitates badly, doesn't switch gears right away, and the exhaust makes a rumbling, popping noise. Also, when I'm idling (not in neutral or park) there is a whirring noise from under the hood, on the driver's side. Before I take this to the dealer (under warranty), I was wondering if anyone else has experienced this or has some ideas as to what the problem(s) might be. I've had no other problems with the car. Oh, I've also been using 93 octane gas from a big grocery chain (Giant) because of the discount on the price. I ran the tank dry today, then filled with Shell's 93 octane today, to see if it was inferior gasoline. I'd appreciate any help! Thanks!

[SilverBullet07]

try replacing your spark plugs. did you remember to gap your plugs when you installed the coil?

that whirring sound might be your cold air intake. they suck a lot of air and are sometimes audible. i have the JLT and i can hear mine sucking the air from time to time

[Ron56]

Thanks for the input! I have changed out the plugs--did it with the screamin' demon coils.

I filled the tank with Shell V-Power 93 octane and so far--fingers crossed--this seems to be doing the trick. There's a pretty noticible difference in power as well. I hadn't realized that different gasoline brands could effect performance so radically! That's what I get for trying to save some coin!