D&R Stang

I'm new to the EFI scene, up until now, I ran a carbereted 69 stang. I got an 88 GT a couple of months ago, and whenever I start it up (hot or cold), it revs up to about 2000 rpm's for about 2 seconds, then it settles down to an idle. I've searched for vaccum leaks and found none. Can anyone shed some light on this? Thanks in advance.
Dave

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Dave & Robin 88 GT, T5
306, polished crank, TRW pistons, underdrive pulleys, cold air induction, 73mm MAF, Xtreme Energy Cam, 3.73's