I don't think the oil level is causing the hesitation or lag. If there was too much oil in the engine it would be smoking really bad. The transmission fluid level, condition and leak may be your cause. I recommend having a trusted mechanic check out the leak and advise you on what is causing it and what the cost would be to fix it. At the same time, the mechanic can check the transmission fluid level and condition and advise you on that as well. The more you know about your car, the easier it is to figure out if it's worth fixing, even if you just bought it two days ago. Let me know what you find, thanks.