1990 Accord stalls stalls

[ILLakeview]

I have a 1990 Accord with 66,000 miles on it. A week ago it began stalling when I press the gas after a complete stop. The rpm dips below 1 and it feels as if it's not getting enough gas. It also shakes when in park. The S (sport) indicator light also turned on but was not blinking. My mechanic thinks it could be one of two things. Either the car needs a new (used) transmission or it's a problem with the transmission's computer. He said the car is driving as if it was a stick shift (it's not) and the clutch isn't pressed all the way. He said the S light was a wiring problem.

 

The mechanic wants to get a new/used computer to see if that's the problem. If it is, the estimate was $225. If it's not, the estimate is $100 for the part and then I decide whether to replace the transmission. Transmission estimate: $1500

 

He also told me the car needs a new shifter cable. The shifter is really sticky, particularly going in/out of park. It takes a few seconds for the gear to engage when you move it from park to reverse or reverse to drive. Estimate: $450 (parts, labor, tax)

 

Even though the car is 22 years old, it has relatively low mileage. What is the likelihood that a transmission in a car like this would go bad? How long do they generally last? Anything else that could cause this? Are these estimates reasonable?

 

Other info to note: Car is kept outside on the street in a metro area. The transmission fluid was last changed in 2009. It was my grandmother's car, so I know its maintenance history.

 

Happy to provide additional info if it's helpful. Thanks in advance for any ideas.