Hard starting, should I be worried?

[Ripper]

For the past week, the GT is having some trouble starting after long periods of rest (8-12 hrs). The battery indicator shows there's plenty of juice but at start up the car fires up, bogs to almost stall, and then fires up again. Could it be the heat and humidity here in the Northeast, which has been miserably lately? Or could it be something internal to the engine (timing belt)? Thanks.

------------------
************************
1999 GT - Laser Red
K&N, Steeda pulleys, Steeda strut tower brace & Tri-ax
(Upcoming mods: subframes (bought), Bassani X (next), & FMS 3.73s