Ten miles to gallon MPG and running rough?

I just got the truck listed above. The previous owner told me that it runs rough. The idle screw needs adjusting, it smokes. He said that he thinks someone had put too much oil in this rebuilt 2.0. He told me in the past Dobbs auto repair told him coolant temperature sensor was bad and that they had replaced it. He returned it with the same running rough and poor gas mileage. They told him there were two other such sensors they replaced sensors. It then worked fine. He seems to think that this is again the problem that he thought that's what blew the last engine. It's a 15-gallon tank and I'm getting about 130 miles. First-second gear is horrible, third okay fourth seems to smooth. The smell of gas is bad and the smell of exhaust gas. I could probably ignite the exhaust if I lit it. I changed the plugs, they were coal black, and changed the wires. The cap and rotor were as good as new. So, after comparing I returned those parts. I am thinking the carburetor needs an adjustment and valve adjustment. Can you send directions to both? I'm definitely considering a new carburetor, so should I get into the valves? One day I unplugged what I thought was this coolant/temperature sensor, no change. The next day it ran great fired up easy performed like I figured it was supposed to, but that was to last long. Then I discovered what I unplugged was the oil pressure sensor.