On my 89, the fuel pump relay did not work(a new one), the IAC valve did not work, and the OBD box did not work(no codes no nothing). replaced a pink label ECU with a good 951, and it fixed all three.

On my 92, the IAC did not work, it was running crappy(low power, rough idle when cold, surging for the first 30 seconds driving.) I did not have any codes on the OBD. Checked the ECU....pink label, replaced it and now the IAC kicks in as it should on startup, and it immediately fixed the drivability problems.

I did many other troubleshooting measures before I replaced the ECU's.....on the 92, about 6 years of wondering what was up with the IAC

There is a lot of info on the board about pink label ECUs, and how they are ticking time bombs....and my thought is since they were bad years ago, they are getting flakier every year. Our 240s aren't getting any newer. Conventional wisdom here on the RWD is that the white label 951's are reliable. This may be a stab in the dark approach....... I like to think of it as a stage zero approach to troubleshooting a 240.