98 Corolla Sputtering/Stalling

1998 Corolla VE manual transmission with 165,000 miles. Had major tune-up (fuel filter, spark plugs, air filter, wires, power steering fluid, pressure p/s hose)exactly one month ago because the engine was "running rough" according to the mechanic. Ran fine for 3 days, then would not turn over. Got about half mile down the road and battery died completely. Replaced battery.

For the last week, car has sputtered at take off, with puttering sound coming from exhaust pipe. Today, during a 80 mile drive, car stopped accelerating at 65mph no matter how much gas I gave it. Then would suddenly accelerate again, until I let my foot off the gas for a second then back to hesitating and sputtering. Cycle continued until I had to stop.

When I stopped, car stalled. Cranks strong, but would not turn over unless I gave it a lot of gas. When I took my foot off the accelerator, tried to stall until I depressed accelerator again.

Got home and turned off car, tried to restart. Started up with some difficulty (lots of sputtering and hopping/shaking). In general, not running well.

Car tends to burn oil during long drives. I have to top it off once every week (or more if I drive a lot that week). Mechanic claims this is not a problem. Use 20w/50 at his suggestion. Topped it off today.

I want to take it back to the mechanic, but I need to have some idea of what the problem is because between a new battery and the tune-up, I've spent $700. I love my car and I'm not ready to give her up. Is this something that can be repaired or is it just time to upgrade?