Small Engines (Lawn Mowers, etc.): snowblower has not power, craftsman snowblower, bit of power

Question
I have an old Craftsman snowblower model # 503-690512 with a 7HP Tecumseh engine. Last year I put a new plug in it and it was running good. Sometime during the winter it lost quite a bit of power in high throttle causing evertyhing to slow down and the snow to just dribble out. This year it started on the first pull but I had forgotten it had no power. Had the carb rebuilt by the local Hardware Hanks mechanic and it still has no power. Starts up great, idles great but put it on high and it misses or something? The all of a sudden when I had it running trying to figure it out, the engine ramped up to what it should be for no apparent reason. Put it in a snow bank and the snow flew like it should. Stopped blowing snow and it lost power again. Tried to stick in the snow again and the power never came. Any idea what would cause the engine to not run high enough but occasionaly find the right speed but with no apparent rhyme or reason?

Answer
I think you should focus on the governor adjustment and the linkage that leads to it.  When you installed the carb back on the snowblower, did you by chance bend the linkage rods?  Did you put them back in the correct holes?

I would be looking at the govrenor system to start.