When letting off the gas on my 22re (87 pickup), the idle would momentarily drop to around 300 rpm for a second and then return to normal. I thought I would start troubleshooting by cleaning the TB with TB spray cleaner. That seems to have solved the problem, but now the idle is surging or sometimes just fast (like 1800 rpm). Any theories on what might have happened? I was thinking maybe some gunk got into the IACV after the TB was cleaned? Or maybe something else got plugged after the cleaning?

 

...just noticed my coolant is slightly low....I'm hopeful I just solved the problem. Will test it tomorrow and post back.