My car when i first turn it on cold it revs to about 2k and then it stumbles to abot 1 then kicks back to about 2 until warm. At idle when warm it sits around 800 rpms.

When i back up slowly gasing it as i back up, it back fires and again the idle stumbles but it does not shut off.

When I am driving it - if I ease the idle back to normal with the gas pedal it goes back to normal. If i am driving and at 3k and clutch it the idles goes down and turns off. This does not happen all the time, but I would like the idles just to go back to normal.

Does anyone have any ideas. I just replaced the fuel filter and it still does the same thing.

One thing i must add is that on the oil filler neck i see where a lateral hose plug goes and it is just opened there is no hose hooked up to it. I think that is where the pvc valve goes.

Thank in advance,