Q: engine noise, sluggish, leaks

I have 2 questions. 1) When I step on the gas I feel and hear the engine roaring while driving, but it doesn't go as fast as it should I can tell because my brother's 2004 DTS flies when you step on the gas pedal. When I put it into 3rd gear it runs normally, but when I put it in drive it doesn't act right. It's leaking about a dollar size puddle of transmission fluid. I checked the fluids and they are all good. Do I need to replace the tcc solenoid? Could that be the problem? 2) I came home today and parked my car in the garage. 2 hours later it leaked oil the size of a soda can. I moved the car to make sure the leak was from my car and the same thing happened 2 hours later. I checked all the lines going to the motor to see if one slipped off or was cracked and didn't see anything wrong until I looked under the car and saw oil dripping slowly. I checked it yesterday, and was at the regular level. When I looked today it was almost dry. When I lifted the hood my motor and radiator cover had some oil on them. I did a scan on it and didn't get any codes for the motor. The only codes I got are p0174 and p1860. I can tell the difference between motor oil and transmission fluid, and I didn't mix them up. What is going on with my car? Thank you.