I think I have a ghost in my truck....

I have a 1999 Ram 2500 Turbo Diesel and it's acting quite strangely.

There's some days where I have no issues at all and then there are other days.....

I'll be driving down the road and the tach will go crazy and then drop to 0 RPMS. And then the check engine light will come on. After a bit of driving the tach will resolve itself.

Then there's other times I'll be sitting still with my foot on the brake and the engine will rev itself up for a moment. it will usually rev up for 2 or 3 times and RPM's will drop to 0 and check engine light will come on.

And when I say rev up I don't mean like a drop in current from the alternator. I'm talking taking my foot off the brake and the truck will speed up and you can hear the engine whining up.

As soon as I shut the engine off the check engine light will disappear and when I take it to any of the local auto shops the computer is reading no error codes have occurred.

So I have a self accelerating truck, 0 rpm's, a check engine light and a computer that will throw no codes.

I was thinking ECM but I'd like to know others thoughts on it before I invest the money.

Thanks!