just recently swapped a b16 and when car is cold and i start it and let it idle, the rpms jump up and down. it'll lag and then go back up. not exacty sure what it is. any suggestions or ideas on what's goin on??

 

My car does the same thing... But some people tell me it's normaL but still i don't think so. SO i would also like to know?

 

Check ur ECU if it's firing any codes

 

Up/down idle is NOT normal. If you do a search on this subject you'll find at least 100 hits about idle problems. In most cases they are caused by a vacuum leak, faulty Fast Idle Valve, a clogged base idle adjustment screw, low coolant level, mis-routed vacuum lines, or harness plugs swapped between sensors.