Change in fuel consumption

[joaqslam]

I used to get 220miles to a full tank of gas with a stock truck only with a CAI installed. I recently noticed that i am now only getting around 185miles with a tank of gas.
The only thing different i did in my last oil/plug change up was to gap my plugs in the .034-.036 range as opposed to the OEM/out of the box plug gap.
Could this be the cause of the increase in fuel consumption?
Truck is a 99 stock with CAI and nothing else.

 

[Modular Racing]

The simple answer is yes, the smaller spark is more potent for lighting a very dense mixture but not optimum for efficient burn at cruise speeds as the spark is more shielded.

MMR
Modular Mustang Racing

 

[2001SVTTRUCK]

What he said ^

Man I'm getting 290-300 miles when the light comes on and I got a 4# lower, trickflow cams, CAI and SBTB. I'm guestimating 400ish hp and 500ish ftlbs.