strong gas smell

[my9250GT]

I have a 92 5.0 GT with 130,000 mi. and very minor mods like a bbk cold air induction and 3:27 gears.
Sometimes i get a really strong oder of gas comming from the passenger side engine firewall near the charcoal box.
I have followed the fuel rails down and everything is tight and secure no leaks or bad hoses can anyone tell me where this is comming from i also have a 94 explorer with the same problem and i can't figure it out! can anyone also tell me if the 3:27 gears were a upgrade option on this year mustang because every one i talked to says those gears come stock on cobras's from the factory and when i ran my vin number thru a carfax vehicle report it came up as a 1992 cobra it clearly is not any ideas?