So I've just had a ton of work done on my 09 SV. 108,000 miles. New thermostat, radiator flush, new plug for the alternator, new alternator, pulley, and tensioner, NGK iridium plugs, NGK ignition coils and boots, valve cover gaskets, big 3 upgrade with 1 awg, die hard platinum battery, rotate n balance, and alignment. Car runs like new. I have 1500 watt system with the factory alternator and the big 3. (Just trying to fill you in on everything) when I drive it runs great. When I start it cold it fires right up. But when I start it again I fires right away but that first initial rev is sluggish. Also I hear what sounds like liguid in my dash for the first few revs. Think that's air in my coolant. The sluggish rev is what I'm concerned about. You know how when you start your car in turns over n does a quick rev. Well my quick rev is sluggish. Only the first one upon starting. Then fine. I'm adding a second battery today and gonna get the air out of the coolant. Just surprised the dealer didn't do that, not right anyway. Nissan did all the work for me. $3250!!! I'm tired of spending money on this thing. Just want it running new again. Want to be able to trust it again. Any suggestions on the sluggish rev? I'm thinking Iay need more battery power due to the system I have. Like I said it fires instantly but that very first initial rev upon start up is sluggish. Then everything is fine. Will air in the coolant do that? I also saw what looked like steam coming out of my exhaust, only once. Haven't seen it since the one time. Sorry this is so long. Just trying to be thorough. Thanks for any help!

 

Well you do have water lines to the throttle body ostensibly for your "choke" functionallity. I guess it is possible that an improperly "burped" system could have a deleterious effect on idle operation on start