I was driving my RX-8 when my car started to die down I had to pull of the road 3 times till I made it to a stop sign and died on me, had it towed. Had a garage diagnostic the problem and the engine blew. Just had a new engine and parts put in at a Mazda dealer where it's at now but they claim it's not running so good and wanted me to pay for a diagnostic to see why. Why should I with the new engine it should be running good?