fan speed problem

[djmunster]

Did the upper manafold gasket , after was done my. Ac was running hot and very low speed even with the fan on high, thought it was the blend door because I've been hearing it tapp when I swiched from heat to ac , did the whole blend door thing , had it cool but no power , looked and looked and realised i. had a vacume line diconnected from that damm round black ball on the wheel well , ok so now I have my ac back but the fan speed changes intermittently it will be blowing out full force then it will just trickle out , I can fix it by turning the speed knob back down to low then high again,, and I also noticed it sometimes happens when I hit a bump , but not always
I checked to see if any loose connections or vacume but I don't see anything out of the ordinary
Any ideas
Thanks