First of all Thank You for taking the time on your reply!

I agree with you that is is a voltage issue.

Yes I do have a tach signal.

So the motor will always crank when key is turned over. However when it is acting up there is no power to the fuel pump, pcm etc... so my question is what could be affecting the power to all those circuits ( I currently don't have a schematic). Also if it runs fine sometimes as in the video is it safe to assume the issue is not PCM related?

I have checked all battery cables and ground connections. I still can't help but think it has something to do with originally frying the IAC. I had to put a new pig tail on it as it did melt it. The issue is only with the starboard motor.

Engine serial number is 0W378033

Swap PCM's from star-port motors to rule that out.

Next time it does what was in the vid, put your finger tips on top the relays. The MPR will click ON and stay ON, the FPR will turn off after a few seconds.

The PCM applies a ground to pin B-4 which activates the relay. If your not getting a click, I would remove the relay and use a meter to see if the pin is going to ground when key is turned ON

[ATTACH=CONFIG]565378[/ATTACH]

Check your cannon plug on the back of the engine. Mine was doing something kind of similar....found a broken ground pin in the cannon plug, causing an intermittent loss of power to the helm (key switch)....mine wasn't as bad as yours, but it would randomly shut off while going down the lake, and them come back alive. I could also sometimes turn the key while on the trailer in the garage, and had to bump the cannon plug to get it to make a connection.

Here's a vid I took of what I'm talking about. The pin should NOT turn freely in the molded connector.

https://www.youtube.com/watch?v=FEu7YVVgDuk

When it is being erratic the relays are all clicking on and off. However at times no relays or anything will click no power to pcm either. So what sends power to PCM AND MPR?

How many years did that take you to find? Holy crap!

That is a very good possibility! I could have pushed on it or something when replacing the IAC.

I'm not gonna lie....I swapped ECUs between engines, swapped a bunch of relays, checked a bunch of wiring, replaced a few other parts, and cussed a LOT while chasing this down.

Happened to find it while spreading out the pins on the connector in an attempt to rule out a bad connection there.

Well I got a chance today to put it on the hose and came to the conclusion that the ECU is the problem.

The starboard motor (the one that cooked the IAC) would fire up then die within 10seconds. Swapped with port motor and it would run fine. What was weird was when I would put bad ECU on the other motor and it would stay running. It would throw knock sensor codes and sound the alarm every minute or so but it wouldn't die.

I figured I would send the ECU to whipple.

word of the warning for the unknown Taking the good PCM and putting it on the bad engine can be one way to knock out that good PCM = it very wise to start with the bad PCM and put it on the good running engine and see how its runs.

Then see if it is matching all the engine running parameters in the scan compared when it running with the known good PCM. You have to scan both times before the PCM swap and after with the unknown possible bad PCM. .

Thank whomever I have never knocked out any PCM's because I would not risk the testing of the known good PCM that way but always took the unknown PCM and put it on a known 100 good running engine. I say this because I know boat owners and even so called good techs doing this and ended up knocking out a good ECM / PCM.

The 600 SCI with a bad coil(s) is a prime example of this -Swap and plug a good known PCM in and power up - crank over engine - bad PCM that was good 2 mins ago.

Most likely I could test this PCM as well. My experience has grown a lot in the past 2 years for ECM / PCM testing and some even repaired.

So what fault codes and any spec parameters out of spec ranges on the scan with swapping the good PCM over to bad engine, now runs good ? also you are testing unloaded and below 2500 rpms as well that might not give you the total picture --- but it could as well. Just saying.