I'm no expert either but have the same 2000 year van and did the DPFE change and intake manifold rebuild as you did several months ago to clear the P0171/174 codes. My codes cleared and have not returned, thank goodness as my emissions test is due next week.
The plastic rattling sound you hear sounds like the symptom others have described where the upper plastic plenum assy. cracks or breaks and makes this noise. Did you inspect it well when you had it all apart? Did it go back together well w/o any binding or possible assembly damage?
The part in your post that concerns me is the cleaning of the MAF sensor with TB cleaner. In researching some DIY activities on my Windstar, cleaning of the MAF was mentioned a lot but with warnings about only using a special cleaner designed just for MAF. I bought a CRC product and cost about seven bucks a can at AutoZone. I've read where any other type of cleaner will kill the $100+ MAF sensor as it is easily damaged by the wrong type of chemical spray. Hope yours is okay.
Some of the other great knowledgeable posters will surely know about the new codes you're getting now and help you out. Watch this thread, I am sure you will get some good tips to follow.