I've come across a problem that is starting to drive me a little nuts mainly because I've spent so much time, effort, and money completing this 1993 Escort GT engine swap into my '91.
What's happening is the car is stumbling under abrupt throttle inputs off idle, and also stumbles under high load conditions in the lower RPM range (usually).
The car is throwing a code 9 for water thermistor open or short circuit, which seems odd as this is the same sensor I used on the previous engine and it has been carefully handled, etc. I will replace this with a known good tonight and report back.
Also, I am using the Flyin' Miata throttle body adapter plate to use my 1.6 TB on a 1.8 intake mani. I have the air inlet to the ISC plumbed into the intake, but the coolant lines are just capped right now. I hear many people have done this and it should only affect idle quality and not cause this stumbling.
The timing was set correctly and the engine runs great if you're easy on the throttle and in the upper rev range.
What do you guys think? Are there any other variables I should be looking into, ideas?