Ignition Coils-replaced all 4 4 years ago, seem to be having the same problem again, whats the life expetency on these things

 

What kind?

OEM original, Rev A and B last about 30k miles max. Rev C should last longer but I haven't seen a conclusive number yet.

BHR should be a lifetime option, as well as other reputable aftermarket coil kit.

How you drive your car will also have a effect on them, as well as the climate. These coils sit on top of the engine and that's part of the reason early OEM versions have a short life.