I have a "basic" singer too -- and man is it tempermental!
I was having the same issue - having to adjust the tension every few inches of sewing.
3 Things have helped:
1) unthread the entire "beast" and drag out the manual and rethread - i was doing two things wrong, and had been doing them wrong from 2+ years!
2)make sure the bobbins are wound TIGHT -- there were a couple that wound loose on the "automatic" thingamajig - and those bobbins would fight me the entire time
3)change the needle (found out from the boards) -- it sounds crazy, but it really does help.
I'm saving up to get a machine I can do free-motion with...