So just got done swapping in a b20 in the integra the first start up and every thing was nice. but today i went for a drive i see the in neutral or in 1st gear when im stoped the rpm jumps up and down for 1000 to 1500.

 

my other LS did that...friend told me it was idle control...but idk...

 

Check the iac and make sure the coolant system is properly bled.. I have an odyssey at my shop with the same problem (didn't have time to check it out today) ill look into it tomorrow and let you know what I find

 

Check the fast Idle thermo Valve it gets loose on theese old things and can cause this

 

So the idle surges?

Didn't think B20's have a FITV.
Is your IAC hooked up correctly?