It may the the technique. Get all the 'slack' in the belt on the span between the cam sprocket (and the tensioner) and the crank sprocket. The rest, two spans, should be tight.
With the marks lined up for cam & crank, and aux if needed, release the bolt holding the tensioner in the 'un-tension' position. The tensioner should snap against the outer side of the belt, between the cam & crank. The other spans should not do anything.
After, rotate the crankshaft 2 complete turns, all the way back to TDC(crankshaft keyway @12:00) and check the marks.
I used a tire iron to back off the tensioner, after loosening the attaching bolts, then tighten the one bolt on the slotted area of the plate. After you release that bolt to tension the belt, tighten the other tensioner fasteners, then do the rotation.
Are you sure you have the correct belt? (I know little, but do know that there are two styled of teeth - square and round - maybe you were supplied with the wrong one?) Do the teeth match the old belt style?
tom
Tom's advice is quite good- I did this job myself on my 96 2.3 a few months ago.
The cam sprocket is quite a pill to keep in the right position. What I did as I recall is figure out what size wrench or socket was needed for the bolt holding the cam sprocket on, and I used that to help me hold the cam sprocket where it needed to be while putting the belt on. It was tricky to manage. I ONLY rotated the cam sprocket in direction engine would rotate it, so as to not accidentally loosen cam sprocket bolt. I also pulled out all the slack in the belt between crank and cam sprockets while installing the belt; I pulled the belt tight onto the cam gear, while it was firmly seated on crank gear (the crank gear which of course, really isn't going to move on you while doing this, but I had truck in gear with e brake set as extra assurance). Once I was sure I had the belt tight between the crank and cam, both in correct positions with no slack in belt between crank and cam, I pulled the belt taught across the oil pump gear (again, all marked correctly to the best of my ability), and then let the tensioner go and hold it all in place. It is tedious but with some creativity it is not so bad. On my 96 2.3, I could not find timing marks on the cam sprocket or oil pump gear, even cleaned up... hopefully you do not have that issue but it sounds like you don't. I had to take an educated guess and adjust twice. Thank gourd its a non interference engine!
One extra important note!!!!! If you have rotated the cam gear independent of oil pump, it is likely oil has drained away from the top end to some extent as a result. This is why often when you see videos on YouTube of people doing the 2.3 timing belt, at the initial startup the top end sounds AWFUL. Because they caused some oil to leave the top end and then started the engine like that. So, once you think you have everything lined up correctly and belt is on, be sure to either crank engine with the throttle full open (as long as your throttle cable opens throttle plate fully, the computer recognizes this as "clear flooded mode" and will not start, just crank), or pull fuel pump relay or trip inertia switch (best to try with throttle full open in case any residual fuel pressure is able to accidentally start engine). Any one of these methods will crank the engine, but not start it, but again throttle wide open is best IMO. The idea being you are turning the engine and thus oil pump, with engine not running, so you do not have a dry start (lack of oil in top end).