mr-blue32

I HAVE A s2 RB25DET in my R32 and at warm up idle speed there is a tiny miss in it but once its warm and the water temp is at about 8o+ degrees or higher the idle seems to chase itself and fluctuate between the recommended 650rpm and about 1000 rpm would doing any of this fix those issues or would it be something else? im new to owning a skyline so any help would be much appreciated p.s the motor is only about 68,000kms old and was only driven 7000k's in 8 years and smells a little rich at times so could it possibly be the tune has gone out from it sitting in a shed for so long before being sold to me