2000 Windstar stalling/idle too low

I have a 2000 windstar and it has been stalling out when I start it. I have to keep foot on accelerator to keep it going. It does this in idle and while driving when I slow down or stop the RPM's go below 500 and the battery light comes on and it dies. It always starts back up but I have to keep foot on accelerator to keep it going. I have read it may be IAC so I cleaned that, but no change. I read maybe vaccum leak, but don't know where to start looking for that. I read PCM power relay or Fuel pump relay, or Throttle position sensor, or Idle speed control actuator, or MAF dirty. Is there a way to narrow it down? No CEL comes on. I haven't checked codes because no CEL. Please help if you can.

vac. leak. get a can of carb spray or brake clean and spray all over intake and hoses, when idle goes up, that is where the leak is...

Thanks so much for the quick reply. I found the leak. It was Part # XZ2Z-9E498-DD the U-shaped Vacuum Line. It is right in front and if it was a snake it would have bit me. The boot was on but was loose so I checked it over and over but didn't realize it had to be snugger. When the van was on it would suck it into place but would still leak around it. I cut a piece of rubber hose and slipped that over the nipple and shoved the boot back on. Wa-la no more problems. It is such a relief not to have to start changing parts to find the problem and this repair didn't cost a thing.