Warning!!, I am a beginner mechanic with that all that implies. I own a 2002 Eurovan GLS, it has like 174,000 miles. After a long trip I started noticing a rough acceleration, like it needed tune up. After listening more carefully, sounded like it was gurgling when I was accelerating, definitively I had poor gas millage. The other strange thing was like a loud hush of air coming out from some part of the back of the engine when the engine was cold, and then it will stop with the sound of a relay from the inside cabin. It will last like 5 seconds. (note: My AC does not work, and I turn it off immediately every time the engine starts).
When checking for codes with VSDS, it gave me P0303, P0306 and P1570. I replaced the coils from the C3 and C5, new spark plugs, cleaned the electrical connectors. When I replaced the coils, I realized there was engine oil in C2. I thought probably the gasket on the valve cover need replacement. I started the process of replacing it (Holly F, so complicated in this van), The MAS had oil in it, same as the throttle body, PCV. Cleaned the MAS (which I replaced it couple months ago), Cleaned the PCV plastic crap, replaced some of the tiny tubes that connect to the PCV and the vacuum reservoir (they were cracked), Cleaned the throttle, Cleaned the electrical connectors. After going as deep as taking the Intake manifold, I gave up due time wise.
The ISSUE NOW is that when I start the engine, the engine runs smooth, until reach temperature and the idles goes down, then it has a hard time staying low, kinda wants to die. Acceleration does not help. I started it couple times and same issue, sometimes does not even run for seconds and then dies. I cleaned the codes, I scanned again. No codes.
I wish I knew how to check the pressure stuff and what that means, maybe that can help?
Any ideas?
Check the video.
https://www.youtube.com/watch?v=mQMO8tcFTU4