I have a Bosch 1590EVS jigsaw (relatively new) that cuts like a dream when cutting plywood, however when I cut hardwood, with the grain, it wants to jump and buck all the time. I've tried every blade I can think of (PW blade, wood cutting blade both fine and coarse). new blades tend to be a little worse than older blades. slower speed tends to be worse than faster speed. If I go faster than a snails pace (literally), it jumps all over. Crosscutting hardwood is fine, just with the grain it is horrible.

What and I doing wrong? Any help would be appreciated.