I have cut springs without any problems to lower cars. I cut them with a cut off wheel. You may have to cut a full coil to get the spring to set back in the pocket right . When you shorten a spring, you increase its spring rate so it will make the ride harder. It is tricky to figure out how much to cut to get the ride height you want. Now I would say never lower a car by heating the springs. This is usuallly creates uneven heights, etc. If your springs were cut off properly and evenly, they may not have been put back in correctly causing the leaning. If you are going to buy new springs, I think Jegs has some lowering springs for your application.
Bob