1995 Toyota 4Runner Engine cutting out.

My truck has been a dream for the last 2 years and has managed 85000 in that time without a problem. I've recently moved within 5 mins of work so I walk instead of driving so the truck has not been used much over the past 2 months, and sometimes sits for a week at a time without moving. This morning (snow overnight and a little cold out) I started it as norm. It was sitting in neutral and idling when the revs dropped and it cut out on me. Started again and same thing. Third time it was fine. Drove into town and back with no more problems. But the same thing happened tonight (still cold outside). It seems fine once it warms up. I had the glow plugs replaced and a new battery about 6 weeks ago. The air con belt snapped about a week ago and it's just had an MOT which it passed fine (and had a service at the same time). Timing belt needs replaced in 10000 miles.