91 4.9 high idle + misfire when start

[roosterinmy4.9]

Well the title says all. ..I don't know where to look but I think its electrical it cuts out and idles high and also my needle on my rpms twitch really bad it vibrates between 1500 and 3000 and its not even accurately telling me the right rpm until it warms up

[Jersey_Joe]

Did u scan it? Check engine light on?

[lee reece]

Look at egr valve circuit for problem or vaccum leak? Check timing?

2007 F150 XLT FX2 SPORT - 5.4l 3V 3.73 LIMITED SLIP