I am having a problem with my engine having a vibration, I have taken it to my local ford service dept. several times with partial luck. First I wanted to say that I have 100k miles and have been good about oil change and fuel filter change. I let the air filter go over a little because I did not realize how bad it was but the filter still looked clean on the output side, intake side had dirt/sand falling out of it though. I am the second owner of this truck, my dad owned it first and he is usually good about vehicle care. When I went to ford about 200 miles ago they had to replace my driver side fuel injectors and #5 glow plug. When I got the truck back the vibration was much better however still present. I took it back that week and they replaced the #8 glowplug and said the heater control valve was leaking. I just had to have my alternator replaced because it wasn't doing much but looking pretty on my engine, the shop I took it to asked if I was charging my batteries at night and was surprised to find out I wasn't. One other thing to mention, I have a Diablosport Predator chip in my truck and the vibrations become far more noticeable when the chip is installed, I use the economy tune (if more details on the tune are needed please ask). Also some more potentially helpful information, before the initial repair where my driver side injectors were replaced, I would get the vibration at basically any RPM, the ones I tried most were 1250, 1500, and 2000 which all gave a very strong vibration with or without the chip installed. Since my driver side injectors have been replaced I can barely feel the vibration without the chip in the vehicle but with the chip in the vehicle I feel it quite strongly at 1250 RPM's but I don't notice it at 1500 or 2000, I'm not saying its not there, I just don't feel it. So far I have not seen any kind of abnormal colored smoke but it seems that I am getting less smoke when I floor it from a dead stop than before. Also since the injector replacement, the buzzing the engine makes when you turn the key to the on position is not as loud and its longer, even after the glow plug light goes off.
Sorry for the post being obnoxiously long, I wanted to try to give all information that I felt might be necessary in a diagnosis, if I missed something please let me know.
Forgot one other part, its a 2005 Excursion limited, 6.0L PSD
Thanks in Advance!