Shifting problem

There was a similar thread about this a while back. But here's my problem: my car(99 4R70W) won't shift back down(at full throttle) to !st over like 25mph, sometimes less. It used to shift back from anything under 45. I heard that it could be something w/ my MAF. I installed a CAI about 5k miles ago, but this problem happened about 1k ago.

I did take a circular wire disk out from around the MAF housing. (seemed useless) But like i said no problems until recently. Any ideas?

1 check your fluid level for the tranny.
2 the screen straightens out the air flow, but most "cold air kits" make it unusable.

Yeah i replaced the fluid and filter a couple hundred after it happened hoping to get it back to normal. no such luck. thanks for posting, any other ideas?