A few problems with my Tbird

I just bought this car, and it's really nice. 1995 thunderbird with a 4.6l v8. It has an engine knock, and I've taken the valve cover off and the only thing we could find was some dirt and dust crap where the valve is fixed to the engine. The knock is still there, and I have been told it could possibly be a connecting rod, but the knock seems to go away when coasting. Also, with the addition of some Marvel Mystery Oil, after a bit of driving the knock would randomly go away, sometimes all together, for a while. Any Ideas?

After accelerating rapidly the oil gauge will start to waver a bit and will drop all the way down, and check gauges flashes on and off when the gauge is wavering. When I put the car in park, it would go away and the gauge acted normally. Now it's just looking like that, and the knock was gone again before this happened. Any more ideas?

Thanks everyone

does it do it at any certain RPM? I lost a connecting rod bearing before and it typically only knocked at higher RPM but had occasional low end knock as well. A good engine place should be able to diagnoss it pretty well and fairly easily.

Welcome to the forum. Have you checked the oil level? If you just bought the car I would recommend changing the oil and filter and then go from there.

Engine seized up on me, I'm pissed as hell. The knock was going away and coming back, then got really bad all of a sudden, and then just heard a loud noise and now when I try to start the car, the start just clicks once loudly and nothing moves.

Will a 5.0L V8 from a 87-93 mustang fit in the 1995 tbird? My engine was a v8 so I figured it might, but I want to be sure before I go buy anything.