Do I need new sparkplugs because I lose power going uphill on a highway

run the fault codes for an exact diagnosis but from your description of the problem I would be looking at a failing cat converter as it may be blocking up the exhaust system

By losing power do you mean its RPM is dropping a lot even when you apply more gas? When you get on the highway and try to speed up does it seem hesitant or sluggish as well? This may be do to bad vacuum lines or a restricted air intake. Check the usual suspects like the air filter, spark plugs, spark plug wires and connectors. Check the power cables to the battery and alternator along with anything else. It may be that when your at an angle, a loose connection is falling back and causing the power loss. Me thinks this is the Spark plug wires, there may be a bad one in the bunch. While the car is running, get under the hood and wiggle the spark plug wires and if you get a bad one you will hear the car doing what it does when you go uphill. You can also check the vacuum lines as well.

sounds like the catalydic converter is plugged/partial blocked- replace

sounds like it's starveing for gas or your sparkplugs are not fireing right or your getting to much gas from your fuel ingector.

Clogged fuel filters can cause these symtoms. restrict the flow of fuel. this could cause a lean 02 code.

Have the fuel pressure regulator checked out.

Fuel filter is the main culprit when you lose power going uphill. Going level or downhill means that the engine doesn't have to work all that hard and doesn't demand much fuel, so a partially clogged filter can usually flow enough to allow the car to run smoothly. Going uphill requires signficantly more fuel, and if the filter is clogged up, it won't be able to flow enough fuel. This will bog the car down and cause you to lose speed. Change your fuel filter.

when was he last time you changed the fuel filter ? change it and see how much cramp is in it ina glass

Next time this happens, pull over and unscrew the gas cap. The vent may be clogged.

Otherwise, your catalytic converter may be failing. It can also clog and hinder engine exhaust.

Good luck !

check the fuel pump as well to see if you are getting the right amount of fuel if not the pump itself may run about 20 dollars or so , check timing as well just to see if your off if you have an advance on the distributor and if you go over 40 if it pops back up its the advance {had that problem once before }