few problems with the new car

[rb26deTgtst420]

So i just got a 93 silvia and it runs well for the most part but im just lookin for help with a couple problems. Sometimes completly randomly while im idling the car will start to blow out s*** of blueish grey smoke. If i turn off the car and then start it again a minute later its gone. It never smokes while im driving it and only rarely does at idle, but when it does its alot of smoke. bad turbo seals? PCV valve? any thoughts? Also car backfires a s*** while im shifting gears and sputters and hesitates. Guy that owned it before me put a fmic on it an said car has no BOV but the boost surge when throttle is closed is coming right back out the air intake then? Ive already ordered a hks recirculated bov so i hope that will fix the problem. Idle is usually fine but when i first start it in the morning it starts perfect then after about 20sec it drops down to like 40rpm an almost dies but it doesnt it just stays running at 40rpm for like 20sec then goes back up to regular idle. Any ideas? Ive changed my spark plugs, cleaned MAF, cleaned IAC. Ive spent alot of time reading about these problems and its hard to get specific answers. Any help is appriciated.