Would it be logical to get a computer check from the dealer, then assess if you want them to do the work or an independant? I suspect there would not be a big difference in the diagnostic test? Similar cars often have similar problems, that the dealer mechanics know about, and an independant may have to do alot of parts testing to zero in on the issue. Additionally, in some models some original sensor and ignition related parts do a better job than the generic replacement. I recall owning a 85 dodge turbo and trying generic oxygen sensors and then having to replace it with an original. The dealer mechanic told me privately that for that engine, original mattered...while in some it does not matter as much.