2002 Chevy Impala Gas smell related to computer problems?

On cold startups in the morning I sometimes get a STRONG fresh gas odor. It goes away in a min ute or two. I have taken it to a trusted mechanic who used a sniffer but found no gas leaks under the hood. I think it is related to computer problems and is raw gas being dumped through the motor into the exhaust. The computer glich comes in the form that the gas gauge acts crazy and sometimes I get the Security light and the dead ignition. If I leave the key in the on position for about 10-15 minutes it resets the computer and the car starts rightup. Am I correct about the gas issue and is it related to the computer?