1998 Mercury Tracer ticking engine sound and loss of power

The engine has started making a ticking sound, just after I had the oil changed. The tick is constant and can be loud at times. It ticks at startup, ticks while driving and ticks at idle. Most of the time it ticks sometimes it'll stop at random then start up again? The ticking sound can and does vary in volume and can get quite loud. Someone once mentioned a stuck lifter?

On top of the ticking I have a loss of power at times, again random when it happens. I could be at idle and feel the car shudder and it'll sound like its going to stall then stop and pickup again. Does exactly the same thing while driving, shudder then almost a stall and a big loss in power then picks up again and all is well. This is not a fun feeling if you're going 60mph at rush hour or have it happen as your crossing traffic. Having the A/C on or off, lights, or other electrical items running has no impact.
The other issue I have and I understand these could be unrelated but they've all cropped up right after the oil change. The issue is the car hasn't got very much power moving between 2nd and 3rd gear. It's slow and sluggish moving up but once in 4th its fine, 1st and 2nd gears are sometimes a thump into gear.
I've checked the fluids, oil is golden still just changed, transmission is a pinkish clear color no real smell from it apart from engine not burnt that I can tell. Just had new tires installed, alignment done, oil done, battery replaced a few months ago, fuel filter replaced today, wires installed, plugs are good spark seems fine. There is no arcing that I could find.
I originally thought it was bad fuel, right after the oil change I stopped and the pump was empty I got a small amount of fuel then it cut out, I tried the next level up and it ran dry too after a few seconds I left and filled up at a known good place, dumped in some of that STP fuel cleaner.

I plan on selling this car next month but can't still it like that it's not running right! I left it into a place today and they said they can't get it to do what I'm saying and claimed the ticking is normal on all small engines they advised $70 worth of engine cleaner they'd put in the oil and gas I said no thanks. I also told them the ticking is not normal it just started which is why I'm here.

I won't be back to that place and I hope I can diagnose it myself then take it somewhere they have competent staff. The people at this place only wanted to read an error code and go from there I'm very far from a mechanic and I could do that myself for free at autozone!


I'd welcome any suggestions, I'm happy to do some trial and error but have little confidence in repairing this car it seems to hate me. Everything I've ever touched on this car I've broken which is why I just have someone else work on it in the end it costs less lol.