I have painted my car twice. Both times I have had blisters appear in various places. The blisters do not appear until several months after what appears to be excellent paint. Getting frustrated! I use Dupont chromapremier base and chroma clear. Any ideas? I use an HVLP setup from TIP tools.

Most blistering problems are caused by substrate problems, the topcoat you used is nice stuff, doubt the problem is there.
Luckily i caught mine when blisters appeared the second time in the prime. Fixed by taking back to metal, etch prime then followed by the 2k. BTW they didn't appear for several days and then only when car was backed out of shop in sunlight(or at least thats when i noticed them).

JimD is right, 99.9% of the time blistering problems are in the work below the paint, either an adhesion problem with the primers and fillers or moisture from the backside wicking through a pinhole in the metal.