Need an Engine Controle Module?

[Weebitob]

So recently after months of disuse I finally get the SVX's rear tires re-inflated I jump started it and am instantly greeted with the 16 flashes of the 'POWER' light indicating a transmission problems. The shift feels quite vague and stiff to move into gear. The car was also took time to respond to accelerate, especially in reverse. So thinking the tranny was gunked or worse so I took it to the Transmission shop to have it taken a look at. After close to a week of waiting they get back to me telling me that the transmission is fine (surprised?) yet there seems to be computer problems so they asked if they can take it to another shop that has OBD1 diagnostics.

After patiently waiting even longer (luckily I can commute by mass trasnit) I finally get back to them and they tell me the car needs a new engine control module. I am surprised because I could swear if it was a computer problem it wouldn't start at all like the last time the MAF sensor went out. To make matters even more bewildering they are asking me to source out the part.

What is the best site to look for an SVX ECU replacement? Also, would simply getting a Stage One ECU and TCU mod be able to take over from the faulty ECU? And can anyone explain if I am right to feel a bit leery that the ECU is the problem at all?