small problems,swapped motors,

[1990civicdxhb]

(I had a 1990 1.5 16v,I burnt the #1 piston ring out of it,so I swapped to a 92 motor 12v with 66k miles,it also is a 1.5,it came with the MPFI,but it already had the DPFI on it,so we changed the motors anyway with the dpfi)

Now when I start my car up in the morning it idles up & down,up & down,then dies,I start it back up & it does the same thing,until it gets warm enough to idle at a steady pace,then it rides fine for the day,
(I figured it could be the dashpot!)

I have noticed it has code 10,IAT sensor,but wheres it at,the haynes manual says its on the throttle body & advanced auto parts says its inside the stock air intake,I have another throttle body with all sensors from my old motor,so its no problem to change it,

I also have a plug thats disconnected on the back of the block,below the throttle body,(theres 2 plugs back there,small one & big one,)its the big one thats disconnected,on the 90 16v,it fit,now on the 92 12v,the hole is plugged,so I have the sensor & a hanging wire!

& for the last but not least thing a matter with my car,is that
I have strait pipe all the way back,performance muffler,headers,air intake,synthetic oil,brand new everything & I very well take care of my motor,in all ways & everyday!
all of this & I cant hit 100 mph on the highway,with advanced or retard timing,its slow,I cant beat a civic hb 1.5 stock,4 spd,
were good friends so we've raced a couple of times,
I can only run 20 seconds in a quarter mile & dont know why!
if you guys have any information I would gladly appreciate it,I have had these things a matter with my car for a good 6 months & just didnt want to ask,because I pretty much know everything to my car,but when it comes to searching on the internet everyday & trying new things out,it kind of gets irritating when I cant fix it,thanks alot if you have any info.

[91civichatch2571]

Heres an online manual that should help you out with a lot of stuff.
http://www.binghamtonlife.com/manual/2gsm/default.htm
As for why your car is so slow. Its a 12 valve. Isnt that the cx motor or something? If so then its not gonna be fast... And the erratic idle, that could be a few of things like your eacv, bad vacuum lines, etc.

[CivicSpoon]

I didn't think there was a 12 valve 92-95 motor. VX, DX, LX, EX, Si are all 16 valve and the CX is an 8 valve motor. You sure it's a '92?