Mitsubishi Repair: smoke?, eclipse gst, head gasket

Question
I've got a 96 Eclipse GST manual. 166K Miles.
It's got a 16g turbo, FMIC, 3 inch turbo back no cat exhaust, larger o2 sensor housing, exedy clutch, NGK Spark Plugs & Wires. Don't have too much info on the engine though, sorry.

I've been getting this weird smoke. Doesn't smell like coolant, and it only happens when it gets hot. It happens intermittently as well. When it happens it might bellow out a lot, or maybe just come out a little. It's a whiteish smoke a little blueish tinted assuming it's oil. It's weird because I have gotten the head gasket done recently. Didn't notice anything like that after the gasket change. 3 months later I stated seeing it. I've gotten rid of a lot of leaks, water coming from turbo line, also coolant leaking from bad hose to the throttle body. Still happening. I was told possible valve stems; or need of a valve job. Also read off a few CEL codes. I forgot the actual codes but I remember it translating to a bad Idle Control Sensor. (Which by the way the idle will drop to around 550 and jump up to around 1200 at times)Also an EGR Valve Issue code. Well, with all that said, if I do need a valve job, how much does that usually run? Any other tests / jobs you recommend?  Sorry for the essay, but any help is greatly appreciated.

Answer
Will,
A valve job can be pretty labor intensive and could run you anywhere from $400-$1000 depending on the the mechanic, experience of the mechanic, hourly rate, and parts required.  The best thing to do would be call around to various mechanics and ask of their experience with working on these engines and get a few estimates.  You'll probably want to have the valve guides and seals replaced.  If there are any bent valves, those would need to be replaced.  Your mechanic will probably remove the head again to check the new gasket seating you had done a while back.  And if you didn't have your timing belt replaced within the last 45,000 miles, that should be done too.  You can see how quickly the cost can increase.  Knowing that the dealership usually charges the most for repairs, call them first for an estimate.  They are the most experienced and are sure to have all the parts required.

For CEL code about the bad idle control sensor it's probably true with the 'idle surge' you described.  Either the sensor or the Idle Speed Controller is faulty.  Your EGR valve may just need to be cleaned out.
Good luck!