I have a 3cyl. mitsubishi diesel that is giving me hot restart problems. When it's cold engine cranks and fires on first attempt. Motor runs strong with plenty of power for as long as you want to cut but if you shut it down you have to let it sit for 15 minutes before it will restart unless you are cranking within 15 seconds of shut down. Oil is manufacturer spec., fuel is fresh, and I even ran some injector cleaner thru it. My glow plug switch does not work so I've just been jumping glow plugs directly off the battery for 10 to 20 seconds. Could this have anything to do with it? Also on hot restart attempts motor turn sluggishly but starter is good and battery is new. Service manual gives nothing on this issue. Thanks for any input.