Mine used to do that very same thing.

Now I start to warm mine up an hour before time trials start, I get it up to 195 to 200 then take it back to the pits turn everything off and let it cool off on its own.

have you tried getting rid of the old stall gas out of the secondary bowl? also drain the acc. pump well and get some good gas in there.Its something I always do after an old super stock racer said it helps.Maybe it will help.

To answere some of the questions:

I run it on just the water pump to 190 degrees about 1 hour before time trials, let it soak until about 30 minutes before time trials and then warnm it again on jack stands working the trans, tran brake, so I'm sure the gas in the bowls has been changed a couple of times.

Ignition is a 1yr old 7AL-3.

Monthly engine maintainence was just performed. highest value on leakdown was 4%, compression test was 120 first hit and 230 5 hits. Within about 10psi everywhere.

I am not the best carb tuner, so the fuel curve might be off, but why would that change over the course of the first run to the second. After the first time run of the day the car becomes very predictable

Bob