What Could Be Causing My Horrid Gas Mileage?

Could have a vaccum leak. Hows the drivability?

Couple of things...

Is it possible that the synch code for the "regular" 94/95 ECU is different from the Cobra ECU? If so would that make the chip non-synched in the Cobra ECU? I have no idea, but given the two different ECUs, I would at least check it out. Maybe your chip isn't doing anything?

One thing to also consider that has nothing to do with the car...

Could it be that you got some gas with ethanol content on the "high side" as opposed to the "low side?" I don't know what your gas is like where you're at (Maine), but I know that here (Michigan) I get a tank every once in a while that just runs through. In my wife's car, in my truck, in the 'stang. It doesn't seem to matter, but a couple times a year for each vehicle I seem to get a crappy tank of gas. If the ethanol content fluctuates from, say 10% on the high side to 2% on the low side, I would think that could make a marked difference in fuel economy. I have no idea if this is the case, but it happens. My wife's car has a Northstar engine in it and it is really noticeable when you get a bad tank of gas in it. It has no guts at all, gets pingy, and gets about 16 mpg instead of 23-25. That's a 25% or so decrease based solely on the gas in the tank.

Of course, all of this is pure speculation on my part...

Let's see if I've got this right. You have an ECU from a '94 Cobra with a SCT chip from some other computer plugged in, 36# injectors and a PMAS 95mm MAF with a tune based on a a regular 94-95 ECU (I assume you mean for a GT) and you wondering why the fuel consumption is horrid. Sounds to me that you need to take it back to a tuner to get it set up for what's in the car now. BTW where did the rwhp and torque numbers in your signature come from? Are they based on the tune from the installed SCT chip with the other ECU?

do you have a wideband? IMO its something MAF/o2 related... or a vac leak

I think we (or I at least) am still confused on the EEC and chip stuff. When you noted that there was not a Cbaza-specific puter in there (they all have a catch code), I assumed you had an aftermarket EEC.
Richard and folks like that can answer better than I, but if you went from one of those to a CBAZA EEC (kind of the reverse of what Richard and others have done), I'd bet some of the parameters the EEC looks for have changed. It would be the same as if someone had an RT and a tune for a Cobra EEC and then went to Brand A aftermarket EEC, the RT tune would probably have to change for things to remain the same, as both EEC's would not be looking for the same values and parameters. They might not even use the same reference values.

your foot............................lol

they don't really get worse, its just one small line. I doubt that will effect the vacuum of the car much. i vote the tuner route after you've tested it with another tank of gas from another place.

That prototype computer is pretty cool.