idle problems for 93 240

[93 240 wagon]

My 93 240 has had idle problem since 20k it now has 170k. Currently it will not idle sometimes. just had a tune up with plugs and wires. car runs great, then will bump sometimes when idling. then will cut off like when i stop at a stop sign. i cranked up the trottle cable and it doesn't cut off, but i know i am just by passing the problem. many years ago had problems with the car stalling after it warmed up, like driving to the store then cutting it off going into the store then cranking, driving to the parking lot exit, stopping-car stalls- crank give it gas and drive for 5 min or so car then would idle. The car would mainly do this with the a/c on. went to dealer air mass meter, o2 sensor, and about $1500 worth of stuff twice. nothing worked! I just stopped using the a/c. Can't do that now when it stalls unless I idle it up it won't keep running, but it doesn't stall all the time. Help!