FarmJeep... Don't ever apoligize for doubting me. I'm pretty darn stupid at times and when I try to remotley diagnois a problem I'm often shooting in the dark. Remember, I've only got about a 35% sucess rate answering these questions correctly... but I do have a unique way of looking at problems which helps me to troubleshoot and solve some... the only skill I've ever had.
Even an electrical load on an engine can cause it to die at idle if the load is big enough.
A winch could qualify depending upon the state of the electrical system. That's the rub, it's difficult to diagnois the quality of the system remotely. A problem could be in the regulator pack, the alternator or anywhere between the batteries and the winch or the winch itself. The dual battery system could be strictly non-isolated parallel batteries which could cause all sorts of havoc. See what I mean? From my view here in Wisconsin I may not be getting all the information I need to accuratly diagnois.
A similiar stall occurance would be the drag put on an engine from engaging an A/C clutch. Though mechanical, the clutch drag forces the idle RPM lower. Modern computerized engines will make up for the drag by sensing the clutch engagement and increasing the RPM a predetermined amount. The older engines often had a way to mechanically increase the RPM, hence the idea of using the Sol-Vac solenoid to accomplish the task. As the Vacuum decreases with engine RPM, the solenoid would automatically disengage after being set.
An alternator can also produce mechanical drag if it cannot keep up with the load demanded by the supplied devices. As alternators have become larger over the years, and current demands have become (in total) smaller though the use of descrete devices the condition is rare.
The rarity of this condition necessates the notification. However, because it's rare, the problem is often overlooked and techs will chase their tails looking for a less exotic answer.