The Camaro Club (UK)

Just wondered if anyone can figure out an intermittent problem i'm having with my '94 LT1 Z28?
The car runs sweet as a nut most of the time but occasionally there's a strong Petrol smell as soon as the car starts. This goes after about 10-20 seconds but the idle stays very lumpy and the car seems to misfire when running. It's a similar feeling to over-choking a Carb engine and wetting the plugs. I can't see any sign of Petrol leaking around the injectors so i'm wondering if a sensor could be messing up the fuel mixture?
It first did it last year and i tried injector cleaner and the fault went after about 20 miles driving. I thought that was the end of it but it happened again about 3 weeks ago. I tried injector cleaner again but it didn't seem to make any difference.
The SES light isn't on and there's no error codes showing. The problem is: nobody around here want's to know as regards to checking for faults. The nearest place that will run a diagnostic is CasAm. When i took the car up there a couple of weeks ago the fault magically cleared on the way up and so Tony couldn't find anything wrong!
Now it's back again. I'll happily drive to Castleford if i know the fault will still be there when i arrive but i just know it will vanish again mid journey!
Has anyone encountered this before? Any ideas before i lose my mind would be most welcome
Thanks,
Mel

Had a quick blast up the motorway today and it's cleared the fault again!

Sorry to dig up an old post but 6 months on and i'm still no nearer a solution.
Tony at CasAm thought it could be a dodgy temp sensor causing the car to occasionally have an over-rich fuel mixture on start up. Changing this didn't help so i left the car with CasAm and Tony found a vacuum leak and a small pipe missing which were fixed. He took the car for a 10 mile drive and said it drove fine. It did for me too for about a week and then started acting up again.
He then suggested changing the fuel pressure regulator which i had done locally. This seemed to make a big improvement to the way the car drove: It was much smoother and more responsive but a few days later and there was that petrol smell again...
The Mechanic who changed it doubted at the time that swapping the regulator would fix the problem and reckoned it would be worth putting in a new fuel filter. You can guess the rest!
So, can anyone suggest something which could be causing all this? I get the impression that the people who've worked on the car are running out of ideas and i'll have replaced the entire car before it gets fixed at this rate!
Thanks for your help.

I know this is probably a stupid answer but has anyone actually taken off the tank to check for damage or leaks on pipework from it or maybe a blocked vent pipe or something of that sort. If not it may be work checking.

Nothing sounds 'stupid' right now! The big problem is that the fault's intermittent and seems to fix itself every time i take it to be repaired.
When i had the regulator changed the car had run rough for 2 weeks, i thought at least they'll be able to see the thing acting up but half a mile away from the Garage it suddenly put itself right.
I'm sure my car's got a cousin in America called 'Christine'.

Haha it definitely got a personality then. Im unsure what else to suggest then. Sorry i cant help. Hope you sort it out though. Lee