Help New Isuzu Owner -- Did I buy a Lemon?

I just purchased a 2000 Rodeo LS 4x4 yesterday with 39k miles. It was turning over a little slow when i bought it, but i thought it was just battery related, it seems now that it is taking even longer to crank and will frequently cut itself back of if you dont rev the engine some as soon as it cranks. Sometimes, however rarely it will fire right up. What could be the problem here? I am out of bumper to bumper warranty but still have some powertrain left, but im doubting this is power train related??
Please help me out, I'm starting to get concerened about this.