Given you painted the entire car, I doubt that there wasn't enough flash time. ( running around the entire car, cleaning gun, mixing clear )

Are you using all of the Kirker products for the job? Using a different brands thinner / hardener / or other coats can cause unforeseen problems.

Past that look around for someone that has used your specific products / procedures and run it past them. ( Or even the Kirker supplier / web site ) Have a look as some street rod sites like " HAMB " at The H.A.M.B.