Have you checked for a vacuum leak??Start the vehicle,spray carb cleaner around every gasket,vacuum hose,and vacuum operated component.If the idle changes when spraying a certain area,that's the location of your vacuum leak.Did you check the iac valve and its attached wiring harness terminals for loose or corroded pins??Corrosion will prevent voltage from reaching the sensor.You can connect the positive probe of a voltmeter to the signal wire in the iac connecter and the negative probe to the ground wire.Watch the voltage reading as the vehicle warms up from cold start to operating temp.Voltage should increase during this time.Check a service manual for your vehicles specific voltage.If voltage is correct but the valve is not opening or closing to provide the correct airflow or voltage is way out of range,replace the iac.Check the throttle body for carbon buildup too.Buildup will cause the throttle blade to stick/hang up on the edges of throttle body.

If you feel the need to spend money by all means replace the sensors/valves. If it was me I'd ask did it work right before you changed the gasket? Then why would they go bad now. Go back to the last thing done, the gasket and start there. Is it possible to put the gasket in backwards? Is everything plugged back in?

you have a car trying to adjust to the new parts. actually you may have a small leak near one of the sensors. using a spry bottle of water in the mist setting spray the engine section by section and see if the enging stays more stable than it has been if it does the area where you were spraying is the location of the leak. good luck.

start it up and spray water around the intake gasket ! if there is a leak around the intake you should see bubbles ! also make sure all the vacuum lines and hoses are hooked up !

I replaced the intake manifold gasket yesterday on my Honda and it has been giving me idle problems. Can't figure it out for the life of me. The idle jumps to 4000 rpm and back down. I moved the plugs around and the same thing happens. The iacv and ficv are all cleaned, should i replace them and see what happens? I think the map sensor might be acting up too