1988 Volkswagen Jetta When driving, my car wont accellerate

Its is not turning over and starting properly, I have to step on the gas when starting it to get it to turn over and start. When it starts, it smells like gas and there is smoke that comes out of the tail pipe (more smoke than normal) over all, I have noticed a serious decrease in power, and the car is running rough, and I had a major tune up done to it in the past year. But the main problem is this, when I start driving, it will accelerate, But after a few minutes of driving, I noticed that it looses power, and when I hit the gas pedal instead of accelerating, it just revs up the engine and goes nowhere. Eventually I have to pull over, because my car wont move. No matter what gear Im in, it feels and sounds like its in neutral, when I turn the car off for a couple of minutes, it will go a bit but then it happens again, I have donated and I will buy a manual