Mitsubishi Repair: Eclipse problems, speedometer cable, gasket kit

Question
My car is a Eclipse 95Gs automatic
i had several problems with my car but some have been fixed.
right now my 2 problem with this car are the following , 1 white smoke in the exhaust system , i changed full head gasket kit , i changed the oil ,valve seals, etc i mean i changed everything and the smoke is still f***ing me , 2 my other problem is when i start the engine the rpm is up and down betwen 1000rpm and 700rpm , and when i am driving in slow speed suddenly the car turn off .and when i am braking is the same   
i dont know what is wrong with this car everything is new full head gasket kit .seals , filter and oil automatic transmition

ohh i almost forget it , the car starts in any shift position D,R,N
i recently gone to a computer diagnostic and it showed me 4 bad things: IAC , PCM , Speedometer , and timing belt could be skipped 1 or more thooth . the thing that i am very worried is the pcm ?can you help me with that? i read that the pcm works with the transmition , and can you tell me where is the speedomter sensor or cable to connect it , it worked before but i think a mechanic didnt connect it again , how i can to know if the pcm is broken?

plz help me with any comments

Answer
Cesar: Hey do you know the PCM is the computer of your car, it controls the engine and the transmission. Do you know that Mitsubishi farmed out the building of their computers to another company that did not build very good ones. As piece will start to break down, with time leak into the computer and then with time it kills off the computer. If I was you I would be worried about the timing belt, that belt goes it will take the engine with it. So you need to get that fixed like now!The speedometer sensor is believe at the end of the speedometer cable. If you had a mechanic fix the car before, I would take the car back to him and get him to fix it right. Or find another shop. If the car will start in other gears, then your neutral start switch is malfunctioning. If after replacing the head gasket but still the car is putting out white smoke, I would check to see if water is getting into the oil another way. That is what the white smoke is a sign of, that water is mixing with the oil. Does your car heat or use water? Still you need to get that computer in your car replaced or rebuilt. And that will most likely help a lot of these problems. Next time you change the transmission fluid and filter, remember to put a conditioner in with the fluid. It would really help the transmission. The way to know the computer is not working right, is it is shutting off the car. It does that when it is not working right. You said everytime you slow down speed wise the car will turn off. That would be the computer doing this. So you need to either rebuild the computer or get a new one. Don't go out to a junk yard and buy one out of a junked car. As you need the right model and year to go with your car. Make sure you do this. Hope this helps and good luck! Linda. PS. keep me posted on this.