Help with 2001 Mazda MPV please
 

I have a 2001 Mazda MPV with about 200 000k on it. It has been running very rough lately especially in idle. New spark plugs, coil and wires have been replaced about a year ago. I have taken off the intake plenum and cleaned it. Also cleaned the MAF detector and IAC. A couple of days ago I put a can of Seafoam through by slowly pouring it into the air intake downstream from the MAF. After it sat for about 15 min I took it for a drive where it did it's usual thing of smoking, etc. and after awhile it seemed to run and accelerate way better. Thinking I had fixed the problem, but boy was I surprised when on it's next start up it ran really rough, barely running, has a complete lack of power and it sounds just awful like it's missing on a few cylinders. Thinking the spark plugs got fouled, I cleaned and inspected them but no difference. Anybody have any ideas?