1986 CRX DX idle rough

I really need some help here if we have any Carburator experts. 86 DX rebuilt carb 3 weeks ago. It ran great for 1 week. I had an oil leak and I thought it was rear main seal. I tried some stop leak (seal expander) and Now it is burning a lot of oil (I will change valve stem seals)at start -up. But to get to the point since I started driving it every day gas milage is getting worse and worse and the thing wont idle and RPMS fluctuate real bad below 1500. Today I adjusted the float up and richened the idle air mixture and it will Idle it's still running a bit lean but the idle will be fine for a few seconds then drop to where it almost dies then comes back up again. It is almost a constant fluctuation. I am thinking mayb bad coil but it runs fine at high RPMS. Could it be a vaccum leak, distributor? I'm at a loss. Any help would be appreciated. Thanks

Try replacing your carburator flange ( the mount it sits on) Thats is what happend to us. It was made of rubber and finally rotted thru.

I know it is not rotted thru because i took it off when I rebuilt the carburetor. I used red RTV when i put it back on. Is there any sure way to tell it is a major vaccum leak at the base of the carb? I am spraying Carb cleaner at the base and it does seem to bump the RPMs up a bit. I just think its weird sometimes it will idle fine for a few seconds and then up down up down. Is the engine trying to advance the timing or something makes little sense to me. Thanks for the input and if anyone else has any ideas I would appreciate them.