Astra 1.8 problem

Hi, how's it going? I have a problem with my 2001 Chevrolet Astra 1.8. I haven't had it long, but it's a pretty nice car, though it's not great. It starts fine and runs, but when I accelerate, instead of moving forward, it seems like it's being held back. I've already changed the ignition coil and oxygen sensors, and nothing has worked. It's been tuned up, and still nothing. What I've noticed is that it does it on inclines as soon as I start going uphill, and sometimes even on descents, as if it's braking on its own. Sometimes it doesn't do it, but there are times when I hit a bump, it fixes itself, but only for a little while. I hope someone can help me solve this little problem because I'm fed up with this beautiful Astra. Greetings.

This issue is usually due to a worn clutch or a bad fuel pump; it could also be a valve adjustment problem. If it has hydraulic tappets, you can rule out that issue.

Hey Kikemec, have the valves been adjusted yet? About 15 days after I bought the Astra, the timing belt broke and I replaced it. I also changed the fuel pump, but nothing has changed. Greetings

By "clutch" you mean the accelerator pedal. Regards

No, I'm referring to the clutch kit where the disc, bearing, and pressure plate are located.