Did you put the TB gasket in the wrong way?

Make sure all the connectors you opened up when you did the work are all connected tightly.

-SP

 

TB gasket is good, and all connections are tight.

 

Just a thought, The gasket that goes between the plenum and the intake manifold, there is a little tab or protrusion on one end of it. does the orientation matter with that tab on the gasket?

 

Swapping the a couple of spark plugs wires can cause the symptoms described. Not sure about the Mitsu setup but in Chrysler 3L's it easy to accidentally swap two of the wires because the order on the distributor does not match the order of the cylinders.

 

95 3000gt NA.
1) Just took of the plentum and replaced the plugs and wires and tb gasket and plentum gasket.
2) Slapped it all back together.
3) these problems were not there before i changed the plugs,wires, and gaskets.

So far, reading this, you have created your own problem,
Lets start with 1
What wires did you use, and do you know the firering order and do you know the coil mounting bracket is numbered for wire location? And what kind of plugs did you use?
Next is 2
Slapped it all together. You do not slap these together. Plugs must be torqued to spec, wires fully engaged on the plugs, Throtte body gasket must have correct orientaion and the intake must be bolted down in the correct sequence. Example. Those bolts on the rear of the plenum must not be tightened first. Put them in first, but tighten last, or they can keep your plenum from laying flat. Next you tighten from center out word on the bolt that attach the upper to lower plenum. I do center, than left, right, left and so on. This insures that you have not created an escape route for air. (vaccum)
Last is 3
These are your words. You caused it.
I tend to think you have a leak between your mass and throttle body. You are getting un metered air and therefore the ECU can not compensate for air it has no idea it is getting. Is the mass even plugged in? Coils are #ed back to front 1,2,3 and again, 4,5,6. So the coil farthest from you is 1&4, than moving foreward 2&5, and last 3&6.
Now if want and bought some crazy ass plugs like Bosch+4s. This will make it run like crap as well.
Did you use a service/repair manual, or just wing it.

 

1)NGK regular blue wires, and NGK iridium IX spark plugs
2)I torqued the plugs to 25nm just like the service manual said. TB gasket was installed like it should. The only thing i didn't do was the correct torquing order on the plenum bolts.
3)MAS is plugged in. and i'm positive it's sealed from the intake filter to the throttle body. I would assume the plugs aren't that great for my car or the intake plenum isn't torqued down correctly.

 

Changing the Spark Plugs on a Mitsubishi 3000GT or Dodge Stealth

This is the step by step i used.