poor fuel economy

[rivman1243]

my 92 svx lsl awd is getting horrible fuel mileage. i get about 125 miles per tank where do i start and what do i do. it's got 99,000 miles and the previous owner had the o2 sensors changed at 80,000. i just had the plugs changed about 4,000 miles ago. also sometimes it will randomly stall at low engine speeds like when i come up to a stop sign, this has only happened about 4-5 times. and one more thing some times in the morning when i start it it will have a little bit of blue smoke from the exhaust. thanks in advance Curtis