88 camry, poor engine performance

Hi I have a 1988 camry with 120k miles on it, the engine power is so bad that when i go uphill, I will be stuck at 15mph, I always have to shift to L gear when i climb uphill so that the car can actually move forward. Also, it seems like theres no difference at all whether i step on half or full gas, the car gives the same acceleration even if I stepped on gas all the way on a flat ground.
I replaced the spark plugs and wires recently, and all the fluids were done regularly.

Anybody know what the problem might be?

Try cleaning the throttle body with a solvent. Still bad? Dump some fuel injector cleaner in the tank next fillup. Still bad? Check your static timing. The distributor may be loose or the timing belt may have slipped. Timing ok? Do a compression check. May have worn cylinder walls, valves, etc. Keep in touch.

In addition to what RIP suggested, you might want to inspect the cap, rotor, and the air filter element.

Thanks for all the replies!!

I cleaned the throttle body, and i tried to fuel injector cleaner
but I don't feel much of a difference.

I've also found out that the sluggish and hesistating acceleration only occurs when im starting from 0-30mph, after that, acceleration is really smooh, especially on the the freeway. The car also runs a lot better on cold days, but it still hesistate acceleration.