I used the search and couldn't find similar symptoms and I am tired or living with this.
1987 22RE 5spd
4runner warms up fine but once I start driving and let off the gas the idle jumps from 900 to 1100 up and down (surging). If I give a quick press of gas it idles nicely at 800rpm and everything is great. It does not make a difference if my foot is on the brake or if I coast.

Any advice on what I can check?

Jamie

 

Don't know about your truck but there's a bunch of stuff here dealing with that. Search surging idle or rough idle or high idle.

 

Does your throttle body have a dash pot (prevents a hard/complete fuel shut off when you let off the gas quickly)? Also, check you VAF. I had one on a 22RE go bad (spring broke inside) and it gave similar symptoms.