871 will not idle has been deleted has ran good for 4 years no codes no air in suction line has air in return new inj oring has passed all insite test had fuel leak replaced fuel shut off switch throttle pos ok and new. idles at 800 rpm and surges speed up all air in return go away trying what to do next
Start by assuming the program is a bad delete.. I don't care how many years it seemed to run ok. For all you know, it might have finally or suddenly shifted engine operating modes and is now stuck in a DPF warmup perpetually.. making it run bad. Without first establishing this, it is anyone's guess.
Copy the program out of the ecm and e-mail it to me for a proper review of what someone did. Good, bad, or downright ugly, so that you can eliminate this as a strong factor.... and simply for piece of mind to know you are not using harmful programming that eventually will take its toll on the engine.
also, someone needs to run the overhead valve adjustment on it and do an injector leak test.
ref:
http://rawze.com/forums/showthread.php?t...8#pid67948