Truck has a hard time starting and when started, idle is very high

[Merrill]

Please do yourself a favor and stop spraying starting fluid into it. If you do it too much, you turn your engine into what we call an "Ether Baby" (meaning it wont start without starting fluid). That stuff is helpful if you use just a quick squirt every great once in a while. Using it all the time can and often does mess stuff up.

The fact that you have messed around with the ECU means there could be dozens of problems. However, you should start with the mechanical adjustments first. Things like idle speed are controlled by the BISS and the ISC. One is ECU controlled, and the other is set with a screwdriver. Base timing is also controlled mechanically. No ECU function can over ride a mechanical setting/function/issue.

If your ECU was messed up before, chances are there were a few mechanical adjustments made to attempt to make the truck run better. You now need to go back and find them all to reset the basic operation. Your ECU could have been repaired incorrectly. Im not saying "you did a shitty job" or anything like that... What I'm saying is if you didn't put the correct components in, didn't put them in correctly, or they were shit components - the problem is not solved. There are thousands of variables regarding ECU problems. I always suggest to all of my clients replacing the ECU completely to eliminate all of the variables.

Thats the best info I can give... There are too many things that could be causing everything to not work correctly.

[TALLBLACKGUY]

Regarding the ECU I had it check over by someone at my work who fixes all of our circuirt boards and he said it all tests ok but we shall see!