How loose is your timing belt? Haynes doesn't give any specs re: how much slack there is supposed to be. It just says the tensioner spring is supposed to maintain the proper tension. In my car, the timing belt has almost no slack on the tensioner side, and about 3/16" of slack on the other side.
What procedure did you go through to set the timing? Did you follow the procedure in the manual? If you slid the belt off the cam gears when you removed the head, and then just slid the timing belt back on the cam gears when you reinstalled the head, you could easily have messed up the timing. If a cam gear is even one tooth off its proper position, the car will barely run. Did you at least mark the belt and cam gears with chalk or paint to help you put the belt back in the same place (in relation to the cam gears)?
How did it run when you started it? Did it idle, but fail to accelerate? That might help us figure out what's wrong.
A shop would charge probably $200 or more to set the timing, because they have to take off the valve cover, top timing belt cover, and a bunch of other stuff.
