Nissan Terrano Engine & Drivetrain Problems

If accelerating up to 100km it starts to hop and jerk, or if I am going up a hill. Revs jump around as it is doing it. Had the solenoids on the transmition replaced A year and a half ago and was running fine after that.

Was running fine then suddenly lost power and will not run faster than 2000RPM. I have located a wire that appears to be broken and shows to be live when the engine is running but not live when ignition is turned on but not running

INJECTOR PUMP TIMMNG SETTING

BEEN TOLD THERE IS A FILTER ON THE INJECTION PUMP CAN YOU TELL ME WHERE THIS IS AND HOW TO CLEAN IT.

When driving uphill or at a fast rate the problem of overheating occurs. When carrying passengers as well this occurs. You may also note that the use of A.C unit is in use from time to time when overheating occurs.