1997 Dodge Neon several issues

Engine Mechanical problem
1997 Dodge Neon 4 cyl Manual 149000 miles

I had no choice but to buy this car. When I first got it a while back it ran fine. Just a little slow. I replace the wires and plugs. Did an engine and radiator flush. Replace the valve cover and oil pan gasket a long with an oil change. She ran a little better, but really not much improvement. When I put it into gear to drive the car feels like there is air in the engine by the sound it make like a high rev with a whirling air noise. As if something is not fully catching. She idles a little rough and is very slow to go. I fear taking this car on the interstate do to the sluggishness. It feels like it takes 2 1/2 to 2 times longer than it should to reach any speed.

now where the rubber clutch inspection cover is there is a flow of oil coming from it. Also when I drove it the other day the thermostat never went above the half way mark and smoke came from the engine. And when I stopped the car and turned it off she was making a sputtering and gurggling noise. I looked under the hood and the rad over fill canister was shaking and the fluid was boiling. The color was also rust colored? I had just done a flush a week ago so I am at a lost. Behind that same spot when I got home is where a large amount of smoke was coming from it. I was told the main rear seal needs to be replaced.
please don't say you should not have bought it or get a new one. I am a single mother of three and this is all I could afford. Any suggestions would be greatly appreciated. And a suggestion on a better manual to help me do the repairs myself would help to. The haynes book is not as helpful as I thought. Paying for a mechanic to fix it at this time is unthinkable. I have limited money and little experience with repairing my own cars. Thank you for your time :).