I installed a new cam position sensor following instructions in Hayne's manual, seated it down on the paper spacer, but when I run car it is idling at 1500rpm, very rough. I found that if I break loose the sensor and raise it up about 1/8 of an inch while the car is running the idle smooth's out to 500rpm and runs great, but when I stop car and restart I have to repeat this procedure, putting it back down in order for the car to start and raising it again to smooth out the idle. I put old cam sensor back in and found it doing the same thing. why would this occur??