Hi,
Since the primary trouble seems to be twofold, my first suspect is that the engine coolant temperature sensor is either bad, not connected, or was damaged when the engine was replaced. The coolant temperature sensor monitors coolant temperature. The ECU uses this signal to control open/closed-loop operation of the fuel injection system, overdrive on electronic transaxles, spark advance (ESA), idle speed control system, and EGR system. So, that could be causing several different issues including no start cold, high idle, and drivability issues.
Here is what I recommend: First, check for diagnostic trouble codes that could be related. Because of the model year, this vehicle has an OBD1 system that doesn't require a scan tool to retrieve codes. Follow this link:
https://www.2carpros.com/articles/toyota-trouble-code-definitions-and-code-gathering-method-1990-1995
Next, inspect the coolant temperature sensor for issues related to faulty wiring, a bad connector, or anything that can cause a faulty signal. See pic 1 for location.
If there are no visible issues, I recommend testing the sensor. Pics 2 and 3 are the directions for testing.
I hope this helps. Let me know if you have other questions.
Take care,
Joe
See pics below.
Images (Click to make bigger)
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Monday, January 17th, 2022 AT 6:53 PM