Erratic Speedometer Performance, Engine idle & Fan Operation

[BrianGuy1979]

My 1990 3.1 is has been misbehaving since last year. It only does it when it wants to also. There are times when everything is fine and then out of no where it will hit. The speedometer will start bouncing around like it has a poor electrical connection and then just drop to 0 and the mileage will no longer climb either. All other needles working as they should. The cooling fan will start run even after sitting overnight upon start up with the AC turned off. And lastly, the idle will start to surge....it will also hold 25 mph like the cruise control is on and then when you come to a stop you need to put it in neutral because it is trying to accelerate. Once it is in neutral is when the idle will surge up/down quickly and frequently stall if you don't two foot it. When you put it in gear, you need to be up high in RPM's or it will stall. Hate to keeping chirping tires and doing this to the transmission! It is so old now that everyone that I have taken it too can't talk to it and cannot help diagnose it. I have heard multiple people mention a defective ECM and to also consider replacing the ICM. I can't help but think that the ECM would be the start. There is another post from many years ago but I haven't head back from the OP from a PM on if replacing the ECM was the fix for sure. (https://www.beretta.net/forum/viewtopic.php?t=14424) I think I am just going to buy one and be done with it but wondering if I will need to have it programmed or if it is like newer cars where programming is needed. Wish Aaron was still with us....He would have been my first go to! Anyone else experience this with their car and corrected it? Thanks!