Thanks for this post. I'm having the same issue on my 1999 4 Runner 4WD. I'm about ready to start looking at stuff. I've replaced the MAF 3 times already (running a K&N Air Filter which I found out is prone to mess those MAF's up) so I bought one from AutoZone with a lifetime warranty. Now I just take it in and swap it out. haha. If I find the issue, I'll let you know.