P1138 on Nissan Sentra 2005 1.8L

[slfalco]

Hello, having an annoying problem on an 05 Sentra with 1.8L. P1138 appeared when car was first bought used.. I found what appeared to be a loose connector on the swirl control valve position sensor, which I reseated, and the problem was gone for a few months.. It came back again, so this time I got a used intake manifold, and moved both the actuator motor and the position sensor from the used manifold to the car. Problem again comes back after a week. Could the butterfly valves be sticking closed or open, causing this? I noticed on the used manifold that I got that there are a lot of deposits on the lower intake and the butterfly valves, but I would think that the actuator should overcome this? Unfortunately I will have to remove the intake to check that... Just wondering if anyone has seen any issue like this, and what the root cause was.... I inspected all the electrical connections, I don't see anything there... I guess I could break down and buy the whole intake lower assembly from the dealer, but it is close to $300, so I want to be sure I rule out anything else...