boggs down when its at 3500 rpms

have u checked all your boost lines? sounds to me like a boost leak. do a good boost leak test, ask someone at your local auto zone or parts store about what u need, and try maybe taking off the intercooler and cleaning it out with gasoline or rubbing alcohol. cheap things to do that may help you figure your problem out. all stock? does it have a boost controller on it? boost gauge? stock injectors? stock fuel pump? do a boost leak test and check n clean ur intercooler. thats where id start. hope this helps...

You could have many issues, a misfire from the coilpack, a back plug due to predetonation and even a failing ecu. Start at the boost leak issues first.