running issues can anybody help please?

:cry: Ive got major issues regarding tickover and fuel consumption on my caddy. Just over a month ago i gave it a full service changing the oil, oil filter, sparkplugs, rotor arm, points, condenser, dizzy cap, airfilter, coolant and thermostat and even replaced every vacumn pipe as the old ones looked fooked. I then took it to a local garage cus it was pinking slightly and i had the timing set and it ran like a dream until last sat nite were it wouldnt tickover and when i came of throttle it was backfiring and spitting flames! But it still drove fine up and down the gears til i stopped then it would die. Sunday i went to pod and it was back to normal with no problems at all but since then the problems came back and is doing my head in  Ive checked everything and changed the coil and leads for a new ones this morning but the problems still there  . Any help on this would be great, many thanks in advance