87 pulsar high idle and bog problems

[johnebgoode]

I have an 87 Nissan Pulsar NX SOHC 1.6. 5 speed standard. It runs fine but I have no high idle and it bogs when I step on it. It mostly does this in cold weather. Some background..... It started this after it blew the side right out of the distributer cap and burnt the rotar. I replaced them and I never had a high idle since. It already had the bog problem before this. To make it even more confusing, I have changed the engine and put a low milage engine from Japan in it and mostly all new parts on the engine. Including a another used throttle body. New oxygen sensor and I tried a new temp sensor. The one part that came from the old engine was the intake manifold...it had to be changed from carb to throttle body and for emmissions.
Could it be the ECM??
I figure at least one of you guys out there must have come across a similar problem?
This car is in mint condition and I'm going to get it painted in the spring and this is driving me nuts.
Talking to mechanics is like talking to a door knob.......they want to replace everything on the car until they stumble on the problem.
I've been there.....might as well buy a new car!!
I have more faith in you guys.
Any ideas????
I'd really appreciate it.