Engine Missing or Surging at Higher Speeds

I barely know how to put oil in my car, but I'm trying to learn on the fly what might be the cause of my '92 Metro's problems. At speeds of about 80 km/h and higher, I have to accelerate emtremely slow or the car chugs back and forth like it's running out of gas. There's no loss of power, only loss of 'pull' to accelerate. Inclines are worst. I've read every post on this site and I'm getting all kinds of ideas. I've got a mechanic who has tried a couple of the least expensive fixes to no success. Here's a history...

'92 Metro 1.0 l (205,000 km)

-New fuel filter and cat. converter (7 months ago)
-New cap, rotor, platinum plugs, leads
-'Engine rebuild kit' added 5 months ago to help seal up a cylinder that was burning oil pretty good to get through emmissions test (passed)

Trying to figure out whether it's worth it to try a couple more cheap fixes or not. Reading about all sorts of things to try...
-TPS (I'm ignorant though because I don't even know if it's carb. or fuel injected)
-check all vacuum lines
-burnt valves
-fuel pump
-rebuild the head that didn't test well for compression

Is my engine just going to die? Should I try something else? What should I be paying for an engine? What are my options for rebuilding part or all of the engine, or should I just replace it?

Much appreciated.

have him check the fuel pressure and volume. pressure should be between 13-17 psi and should have a good volume of fuel coming out of return line while car is running

Is your car a manual or auto transmission? If it's a man. it could be a slipping clutch,accel at higher speeds and climbing hills putting more stress on the connection between clutch and flywheel

I'll have him check that over the next couple of days and post the findings.

Thanks for your idea.

have him check the fuel pressure and volume. pressure should be between 13-17 psi and should have a good volume of fuel coming out of return line while car is running


Will have him check and post response.

Thanks for your help.

Also sounds like perhaps your throttle postition sensor is out of alignment. Could just need re-calibration, or replacement.