I traveled 130 miles out of town. Vehicle sat for 7 hours. As soon as I started home had a miss at high speed. Still held spped on highway. Came of highway after about 20 miles and left truck running for few minutes. As i backed out car smelled gassy and acted like it wanted to die. Got back on highway -felt like it was running rough and low fuel mileage. Came into town and after idling at stoplight will hesitate and miss as start up. Left it run at home longer it idles rougher idle got. No check engine light came on. Fuel problem or valve problem most likely.