oseprophecy

ok here's the problem. I swapped a 98 Civic EX motor into my 94 Del Sol. been running fine but lately she has started running low on oil. Not leaking anywhere that I can tell, so she has to be burning it. Also under heavy acceleration there is thick black smoke comming from the muffler. What could be wrong? Also she is still running fine except the burning problem, but if I turn on the AC then she wants to stall whenever I'm trying to get going in 1st gear and I have to rev real high to get going. Any idea's as to whats going on? I know the AC robs some power but this is like 60% power loss here with AC on. Need help PLEASE!!

LSVTECoupe

could be anything from the piston rings.. valve seals.. but usually oil would emit white smoke... black smoke seems to be excessive fuel.....