timing problems

[chiaronate]

i recently adjusted the timing to 10 btdc, and reconnected the spout connector because it was rattling at low rpm. when going up hill at low rpm, i pressed the gas pedal enough to up-shift. i got a serious lack of power after upshifting and had to let up on the gas to pick up speed. what does this mean? i don't have timing marks, so i looked closely and marked where i saw 10 btdc. maybe i marked the wrong place? how much is it to have the timing done at a repair shop? i figure they can adjust it accurately without timing marks, and i can use it as a reference point afterward.