Lately i been experience some idling issues when starting up my 99 Nissan Sentra SE-L. When I usually start up the car the idle drops down from 400-600 rshared_pm. It stays like that for maybe 45 seconds then goes back to 1200 rshared_pm.Today I was driving to work and I was getting on my car and I notice a cloud of black smoke came out of the exhaust. Can this be a tunning issue? Or something else?

Things I have one to the car:

*GTI-R motor
*Weisco forged pistons
*Eagle rods
*ACL bearings
*GT30rs turbo
*550 injectors
*Z32 maf
*Ecu tune from JWT
*Neo safc
*NGK iridium spark plugs
*NGK spark plug wires

 

I would say, based off of what you've said, it is a tuning issue, probably running a bit too rich, which is common for the "fill in the blanks and order your tuned ecu" type of tuning and that has killed the spark plugs.
Simple fix should be just swapping out spark plugs with some new ones.
To really get it fixed, take it to the shop and have it tuned for real.

 

Well I checked my spark plugs this morning and they seem really good, but your right I do need a real tune. I was thinking of buying my stand alone sometime next week.

 

off of the bat, I would say it was spark related.

It could also just be your tune itself... I mean, it has cooled off quite a bit so that could be tweaking with your tune. if it was already on the rich side, then the cooler air is going to make it really on the rich side.