Picture of the ECU circuit board and numbers on the board and case.
Is there an Eprom chip in the ECU (a special socket is installed and can allow removal of the Eprom chip for this)?
Picture of the circuit board with particular attention to the large cylinders (capacitors) because they are very suspect if they have not been inspected and if found to be original, replaced in short order.
We can tell you what ECU you have by the numbers, and what if any chip is installed.
Also, if your ECU has two circuit boards, then that is also a defining feature.
We have a bunch of questions and pictures will speak 1000 words, so we can definitely give you a hand!
Picture of the left side (when standing in front of the car) of the cylinder head. (should be a designation of the type of head - 16, 18, 20 to indicate 1.6L, 1.8L etc)
Intake looks like the Evo3 style.
Picture of your mass airflow sensor sticker (this tells us what type it is) and whether there is a honeycomb anti turbulence device still installed inside.
Picture of the top of the fuel injectors (blue, yellow, pink, grey - this is what we are looking for, and shape - the picture will tell us that).
Once we know what head you have and what intake, we can tell you if the gaskets between the two should even line up.
Also, can you tell us if the motor mounts are located on the transmission bellhousing/case or the motor block?
If it looks like motor mounts are on the transmission side, then be sure to look and see if the block has any mounting points that would have been used previously to mount the engine.
Thom is spot on, because I also, have never seen that thermostat housing or outlet setup.
Once we know what motor you have, ECU running it, and MAF and any chip compensation, then we may be able to point you in the direct of any massive discrepancies (parts that should not be used together or just maintenance and checking all base settings/boost leaks, etc).
Your BOV (blow off valve) could be installed incorrectly or not working properly, vent filter on the side of the rocker cover should be recirculated, PCV valve could be sticking, spark plugs could be in need of changing, base timing could be off, mass airflow sensor could be mismatched, injectors could be the wrong size for what the ECU wants them to be, the list continues. This is why we have to start with what you have and move forward!