Hello. I have a 1998 honda accord lx 4 cly. The cel threw 2 codes. P420 and p401. I decided to work on the egr insufficient flow sympton yesterday. I took off the intake manifold cover and the egr valve. I purchased carburator cleaner and i clean the egr valve underneath and the egr port from the side off the intake manifold to the egr valve. I put everything back together very carefully. Oh yes I also replace the intake manifold gasket. Ok so when I was done I key on the on position and erase the codes. Then I was going to started and drive it around to see if at least the egr code would was gone. But now when I start my car the rpm are going crazy. It goes very high and then low, then high then low. I check for vacuum leaks but I can't tell. Also I check the intake temperature sensor on the side of the intake manifold and is tight but when i disconnect the electrical connector plug i see a little bit of oil inside. I took it off and clean it but the oil came back. Maybe there is an oring that is bad. I spray carburator cleaner alot on the cover and all of the little holes that the intake cover has and also i spray on the intake manifold itself but i am not sure if i was suppose to spray inside of the 4 holes in the intake manifold. I tried tapping on the idle air control valve behind the intake manifold when the car was running to see if the rpm will change because maybe the \valve could be stuck in the on position. I don't know what else to do. Please help!

Thank you