Low idle/vibe when brake pedal pressed

my car idles fine when its cold, around 2k, and comes down after a couple mins, its just hot idling,

Is the idle computer controlled? cause my car shakes a bit at idle even off the brakes…its enough to cause door panel to rattle a tiny bit…and the steering wheel to shake lightly…but if i hold the gas pedal down a lil bit to get the idle to about 950…it stops shaking…can u adjust the warm idle?

I just had my engine swapped to a B18B1, and encounterd that problem. i just came from the shop where i had it swapped, they did a little adjustment on the distributor, and fixed a little bit of the problem, my rpm still fluctuates but not that much, they also said it might be the alternator, i dont know what to do

i have a 96 B18B1 with the same problem stock pr4 ecu. tried replacing just about everything with no fix. still fluctuates at idle. distributor, plug wires, plugs, iacv, fitv, injectors, motor only has 55,000 on it