on cold start i get backfiring hesitating rough idle . unable to go faster than 20 mph even when accelerator fully depressed... no fuel delivery...than it catches and revs to 50 mph....then again no acceleration... after 2-3 miles it will clear itself and run better although still minor hesitation especially when using turn signal or other electrics... fuel pump was replaced 4 months ago...4 days ago major backfiring and explosive noise from exhaust...pulled into service and they said right away my catalytic converter had blown up...since northstar engine i would need full undercarriage assembly at cost of over 700 usd...car was picked up yesterday and this morning i have very same issue of backfiring no fuel delivery hesitating...wtf?.... can no one figure this out?