I know it sounds dumb, but have u made sure the leads are on the right spark plug?
When we washed the engine bay in our VH wagon, we removed the leads, and put them back on afterwards....it had a really hard time starting. It would turn over, and sometimes fire, but not enuf to keep it goin...but after about 10-15 mins of keeping on tryin it got to the stage where it was just run, but like a bush pig.....I even drove it to a job interview.....was the most frustrating drive ever.....it was running like a barge, and a lot of the time it wouldn't pick up speed. After a few days a mate came over and said he'd bet us $10 that we had the leads hooked up wrong. He changed them around, I turned the key and it went like a dream again haha.
So yeah, maybe just double and triple check ur leads, then get 2 mates to do the same and make sure they're right. We thought we had them on right, even double checked.....but still we f**ked up haha.