Antifreeze leak.
 

I have a 1990 Chevy full size pick up with the 4.3 liter motor. Just last night I noticed it started to bog out and all but shut off until I gave it enough gas to down shift. I then noticed my temperature rising. So I stopped and got out to look and had a very slow bud steady drip of antifreeze rolling down and dropping off the oil pan. When I shut the truck off. It started smoking real bad so I popped the hood and noticed the smoke coming from behind the power steering pump. Just trying to find out what this is. Thank you to anyone in advance

Anti-freeze doesn`t evaporate very fast. Hose it off and let the engine dry. Start engine and watch the hoses and water pump closely for the leak.

The water pump on my 4.3 starting leaking antifreeze through the weep holes on the water pump. This is a good place to start looking at.

my 91 has a 4.3 and ive blown a couple head gaskets since the temp gauge on the dash doesn't work and I didn't realize it was overheating. some of those radiators have plastic drain plugs at the bottom that get stripped pretty easy so check for a leak there, its a pretty quick cheap fix if that's what it is. otherwise just hose everything down, wait for it to dry and see if you can trace back to where the leak is