Astra 1.8 problem

That Astra has electronic fuel injection, so there's a yellow light on the dashboard called the Check Engine Light. It should only come on when you turn the ignition on and go off when the engine starts. If it doesn't, it's because some of the engine sensors aren't working properly. You should have it scanned. If it were the clutch, it would only have power in the first three gears; after that, you'd just hear the engine whining and it would have low speed.
If you're interested, give me more details about your problem.

Of course I'm interested, thank you. Look, the car suddenly seems to be slowing down. Sometimes it runs fine, but it struggles on inclines and even downhill. It's like it's braking; it loses power. The strange thing is, like I said, even going downhill in neutral. I already changed the oxygen sensors, the ignition coil, the fuel pump, and nothing. No warning lights come on on the dashboard, and the scanner doesn't show anything. Apparently, everything is fine. I accelerate, and instead of moving forward, it just slows down.

Another thing you mean by clutch is the accelerator pedal or where it's located. Greetings.

Hi! It's very likely your car has a blockage in the exhaust pipe. Please check the catalytic converter, muffler, pipe, etc.
Cheers!

OK THANKS I'LL CHECK IT OUT TO SEE IF THAT'S IT BEST REGARDS