1997 chry intrepid will speed up to 80kms but after that it bucks or surges when you punch the gas at say 60kms to try to gain speed it does. The same thing but no gain in speed

Have you changed the fuel filter lately? Also have you cleaned the injectors?

. Use an advanced scan tool to check for any DTCs and/or pending codes, which may give you a "heads up" on what's going on. It could easily be a problem with the Crankshaft Position Sensor, Camshaft Position Sensor, Oxygen Sensor, Vehicle Speed Sensor (VSS), or MAP Sensor.

. Replace the spark plugs, with the same Champion plugs that originally came in the car, if they have not been changed in the last 3 years. Only use Champion spark plugs in Chrysler products.

. Replace the fuel filter, if it has not been changed in 30,000 miles.