I have a mitsubishi Lancer 2003 OZ Rally manual transmission with 75000 miles. Two years ago I put in a new clutch. It ran fine until this past August when I started having trouble shifting especially after the car had been driven awhile. My mechanic first thought it was the slave cylinder but after checling it out he told me it was an "internal" problem could not work on it What could it be? This sounds like a big deal.what do you think?

SOURCE: clutch pedal stays on floor when released

check the helper spring on the clutch pedal. You'll have to get down in the driver's footwell and using a flashlight look at the mechanism while you push the pedal down (and pull up). If the spring isn't missing or broken and everything looks okay, then change the clutch master cylinder. The piston in the cylinder is probably binding due to corrosion in the bore. I have an 1986 and had the same problem. Changing the clutch master cylinder fixed it.

SOURCE: clutch slave cylinder

Yes, it is located on the passenger's side of the car at the front lower side of the transmission.
You will need the following tools: 12mm and 14mm socket. The slave cylinder could be bolted to the bell housing using either size bolt head.
A 14mm and 17mm open end wrench. The hose to the slave cylinder could be found with either size.
a 10mm combination wrench for the bleeder screw. A small set of vice grip pliers.
Removal and installation instructions for the slave cylinder:
1.Take the small set of vice grip pliers and adjust them to where they just barely close down on the slave cylinder hose. Just enough to pinch off the flow of fluid but not damage the hose.
2. Using the 14mm or 17mm open ended wrench, break the hose loose from the slave cylinder, turning it in a counter clockwise direction. Make sure you have the wrench squarely on the fitting to avoid rounding it off.
3. using either the 12 or 14mm socket, remove the two bolts which hold the slave cylinder to the bell housing.
4. At this point with the slave cylinder lose, have the replacement part near by, make sure you have the copper crush ring with it.
5. Holding the hose, rotate the slave cylinder counter clockwise, spinning it off the hose.
The replacement part should have a small metal rod and rubber cover which retains it to the slave cylinder. Make sure to remove the old copper crush ring and put the new one on the end of the hose. If the part did not come with one, reuse the old one. Spin the new part on the hose and place it back on the bell housing, making sure that the rod fits into the steel linkage which projects out from inside the transmission. There is a shallow hole which the rod should fit in. Holding the part in place, don't try to tighten the hose yet, screw both bolts in by hand and tighten them. Make sure you have them both in before you go tightening anything.
6. Tighten the hose, a good snug pull is all that is needed. you don't have to crank down on the line.
Now you can remove the pliers.
7. At this point you will need the assistance of another person. Have them sit in the car, you top off the clutch master cylinder (the one which has just one resevoir) with DOT 3 brake fluid. See if you can find a small container to catch the fluid in, or just use an oil drain pan. With you stationed under the car with the 10mm wrench on the bleeder screw ready to open it up in a counter clockwise direction, have your friend ready to pump the clutch pedal.
READY?
HAVE THEM PUMP THE PEDAL AND TELL THEM TO "HOLD IT" They should keep the pedal on the floor while you open the bleeder screw up.
Some fluid and air may or may not come out the first time you open the bleeder. Close it and tell them to pump the pedal again. They need to pump the pedal at least 5 times and them tell them to "Hold It" again, holding it to the floor. Don't open the bleeder until they have the pedal to the floor.
Open the bleeder and then close it. Repeat the procedure until you see just fluid and no air coming out.. After the first three times you bleed it, check the clutch master fluid level again. Avoid running the reservoir empty other wise you will be bleeding the cluch for quite a while.
Brake fluid will attack paint so if you spill any on the paint, pour water on it and it will neutralize it. DO NOT GET WATER IN YOUR BRAKE FLUID!!!!
If everything goes well, by the fourth or fifth time you have had them pumped the pedal, you will notice the slave cylinder is pushing the release arm and the person in the car should be feeling a normal clutch pedal along with the "pedal free play" being roughly 1/2 " from the top.
I hope I not only answered your question, but have supplied you all the necessary information should you be up to the task of changing it.

SOURCE: Loss of engine power Mitsubishi 2002 Lancer OZ Rally

Repair Manuals for the Lancer is like Hen`s teeth, however in your case look for the obvious replace the fuel filter, check the air filter also, start with the simple problems first

SOURCE: 1993 Ford Ranger 4x4 clutch slave cylinder

In my experience, the main cause of a problem like this is either due to incorrect installation or not using an OEM slave cylinder! As far as the clutch wear, when replacing a clutch it is absolutely necessary to have the flywheel machined at a machine shop!

SOURCE: i have a mitsubishi lancer oz rally 2002, check

replace the mass air flow meter.Most common fault with the check engine light on.Good luck