1993 Nissan D21 Pickup Truck Idle issues

[Corvette Jabo]

My son Andy has a 1993 Nissan Truck I think it has a 2.4 L I-4. Yesterday after he was driving the truck for a while it had an issue where it would not idle correctly. The idle would drop very low and you could say it smelled a little. When he would let it sit for about 30 minutes it would idle correctly and then after a while the idle issues come back, kind of hit or miss. Anyone have anything to look for?
Jabo

[Russ Jerome]

Look for cracked rubber vac lines along the passenger side of motor and bye fuel pressure regulator. While idling "cautiously" spray a little starting fluid or brake clean around the maze of vac lines listening for idle change. Even though its MPFI it has vac lines to the distributor on drivers side, get heated from the exhaust manifold.