I have an '87 R10 with a 305 in it, and a few months ago the truck would occasionally idle at a higher rpm. It would randomly do it for a while, and then it would go back to a normal idle other times I drove it. It's been idling high more often than not now, and sometimes it will start off...
The days that I noticed this were really hot days in the summer, probably pushing 100° outside. As far as if the temp gauge rises going up hills withour the AC on, I'm not really sure, I haven't taken it up any steep grades in a while. I'm not super mechanically inclined but I wasn't really...
I have a 1987 R10 with the stock 305. My temperature gauge wasn't working properly so I put a new sending unit it and everything seems good now, it will climb to 210° at the middle of the gauge and stay there. But if I cruise down the highway, no traffic and with the AC running, it will...