TB Matching???

[geno5.0]

On Sat I was looking in my 70mm bbk TB and I notice that It does not match up to my Cobra intake on the top side there is a overhang from the intake about an 1/8 inch "ouch" and tapers(sp)down as it go,s and the other side matches fine. So I decided to remove the Tb and grind the over hang down to match the TB after Marking the Intake with white out I break out the air grinder and go to town!! One Hr later I have a nice Smooth transtiton(sp) for the air to flow over. Insted of a strait lip. I re install my TB and hook every thing back up and start the car. It idle's fine with no problem! so I kill it I clean up my mess and take the car for a drive about an hour later as I am leaveing my house I romp on it and the car takes off but there is a red light up ahead so I had to slam on the brakes. When I do the car sputters and back fires and almost dies.This has never happend before.!!! later in the drive it happend one more time after I got on it!! but has not happend again!

Now the car drives fine with no problems!! Seems to pull harder but why did it do this the first time I hit it????
How much do you guys think that this helped (HP)
Was it my EEC trying to figure out the higher air flow?
I pulled all the pulgs No problems there.

OH and I was smart I filled the intake with a Towel and blew every thing out NO METAL IN THE MOTOR
SEE ATTACHMENT TO SEE WHAT I AM TALKING ABOUT