hey! I've been having this problem for over a month now and I think I just solved it! (For my particular truck anyways)

I have a 2000 SR5 4x4 3.4 with 196k. Like I said, for over a month now it's been starting fine when cold, but if I get it hot and stop to pump gas for say, 5 minutes, it would rattle and die when I tried to restart it. Only slamming on the gas would work to fire it back up. So I started reading about everyone else's same problem with their 4runners and the endless possibilities of what is wrong. So, I started at the easiest and worked my way forward... Here's what solved my hot hard start issue:

First, I changed the air filter. Mine was generally speaking pretty bad, we had major fires here in Santa Barbara recently and my filter was full of ash! Probably not causing the hot start issue but, like I said, I started at the easiest possible fixes. (I used some generic air filter from Autozone $20 or so).

While I was under the hood I also decided to clean the MAF. This was the next easiest step, and a very commanly mentioned possible problem, so I got into it.
Once I got to my MAF I noticed it only had ONE of two screws attaching the sensors to the intake! I didn't know what impact that was having on the situation if any, but getting that replacement screw (7.5 mm x 10 mm I belive) went to the top of the list.

So now I have the disconnected MAF sensor out and i clean it with CRC MAF Cleaner ($8). Very very careful not to touch any of the 3 wires with anything besides the liquid cleaner spray. Period. Let it dry completely in the sun for about 20 minutes. I then reinstalled it. Now, at this point I should have disconnected the negative charge to my battery for about 30 minutes so that the ECM would reset but, I forgot.

Now the scary part, the next time I tried to hot start it, way worse! It was a totally different feel. It felt like the engine wasn't getting power now, not just lack of fuel or air like before. Needless to say, I'm concerned now. The next morning (today) I get it started and drive to home depot to get that missing screw for the MAF. I wasn't sure if because I had taken it off and possibly loosened it's seal, and still only having it attached with one screw, that I was maybe creating a vacuum-like leak now throw the sensor opening.

I got the screws, installed them in the home depot parking lot (had to bring my tools because it's way easier to access the MAF if you remove the cruise control module), this time I disconnected the negative charge to my battery for 30 minutes. Attempted to start her up and same thing, super slow, low power, drag out crank. It did start, but barely. But now it feels different. It's dragging the crank, but under that, it feels stronger in a weird way. Not like before when I would try to start it and it would crank really fast and hard for almost 3 seconds and then just barely putter to life.

So now I'm starting to think other things: bad fuel filter was the main one. I am also aware that my trucks computer is now reset and relearning everything, so I take that into consideration too. I get the truck home nice and hot, park it in my driveway and decide to recreate the stopping for gas while warm scenerio. I turn it off and time about 4 minutes, roughly the time it takes me to get gas with the engine off. 4 minutes passes, I crank it, almost nothing this time. I immediately think electrical because now, my electric antenna just barely motors up and obviously, that's for nothing to do with sensors or fuel filters. So now I'm thinking battery.

I bought this truck used about 8k miles ago and I have no idea how old this battery is. I have already called a parts store and have them holding a Wix fuel filter for me because remember, it could still be that. But now I'm very curious about the battery. I take it to Oriellys where they do free battery testing, and wouldn't you know it, bad battery. I buy a new battery, install it on the parking lot and BAM! It's never started so well!

Very long story short, I belive that I was experiencing a two part problem: possible dirty MAF sensor (and it was dirty), and a failing battery at the same time. I hope this MIGHT help a little bit as i know how frustrating this problem is!