ok so what happens is that i start the car up, it sounds fine, but if i pump the accelerator once, the rpms go up, then down, up then down, up then down, and it doesnt stop, it also does sometimes after ive run it for a while and put it in park right before i shut it off. anyone have any ideas?

what year, model and trim are we talking about here?

90 accord ex, automatic

sounds like your engine is "surging". This can be caused by a number of things. Have your fast idle control valve checked out along with your EGR valve.

how would i go about checking these things out? do i need to take it in or is it somtehing i can check out?

The fast idle control valve is on your intake manifold. Look for a thing that has 2 screws and 2 hoses coming off of it. Open the cap and put your finger in there, if the idle goes to normal, then that's your problem. Take a big screwdriver and screw that thing down until it's snugly in there. That should fix it.

The EGR, i would get some carb cleaner and spray it near the gasket, see if it does anything with the idle at all when you do that.

what is the jump from the rpms? cause our 90 accord ex man is having the same problem. The rpms only shift by 100-200 rpms though. The car idles at about 500. thanks for that imput dead head. We've been trying to figure it out for a while now...

icebox, your problem maybe a bit different. If it is just an erratic idle, I;d check the fast idle control valve as mentioned above, then I'd check for vacuum leaks, check your spark plugs, and possibly even your o2 sensors.