Could the ambient engine compartment Temp. be causing a sensor to fail? I have a 1998 Silhouette that has never given me any issues until now. I have replaced the head gaskets twice since I bought it new in '99.
It has 170830 miles on it and I would like to see it make it to 200000.
However when it reaches operating temp it stalls, then starts up again. It only starts in P or N, so its not the PNP sensor. The coolant system isnt overheating and no dash warning lights are on. This is an intermiten problem.

 

Any check engine light/codes? Could be MAF sensor, TPS, dirty throttle bore, bad module, and many more....

 

Off the top of my head I'd say you have an electrical problem related to expansion/contraction. This probably won't be a sensor either as they would usually throw a check engine code. It could be as simple as battery/block/starter connections. It could be ignition/distributor. It could be one of many different things.

The thing that helps narrow this down the most is when you get a check engine light & an associated code. Those will at least point you in the right direction. If you do have a check engine light find out what the code is & post back. Anything else from there, given what you have shared with the board would be mere speculation.

You can buy cheap OBDII readers that will reset your codes online or even at Harbor Freight. I got one at Harbor Freight that had been opened so they cut the price in half. If you look for one at your (hopefully you have one) local Harbor Freight, check in the reduced/clearance items.

BTW you mentioned wanting to get about 200K miles out of your van, I have about 240K, & mine runs like a champ.