Ive been slowly noticing that my car has been getting worse and worse gas mileage. Currently im averaging about 20mpg right now.

About 4 months ago i was hitting 28 regulaurly.
And on top of it my car seems to really be getting soft under 3500rpms, dunno why but its just that seat of the pants feel going away.

But then again on some days i can blow the tires off anywhere in 2nd, and most of 3rd. Its really hit and miss lately.


Its been about 40K miles since my last plug/wire change. And im sure the car needs to be tuned pretty badly.
Any ideas what to start looking for? I know im not giving much to go on.

car is a 94 z, m6 , 3.23's, AS&M cai, coated mac headers/off-road y-pipe, gutted cat, cut-out SLP 2otl, free mods, spec stage 3, SFC's....

i want to wait on sending my pcm off to madz28 until i get gears installed.

 

As your O2 sensors age, they get coated and your car will run rich causing fuel mileage to drop. It wouldn't hurt to put in a new set. Don't know how many miles on your cat but if you have one it might be partially clogged.

 

I think the 02 sensors are nearing the 100K mile mark so yea. Im doing plugs/wires next friday so i guess ill throw those in too.

OMG i hate changing those things.