Loss of power, engine vibration and squeal squeak noise

[bmwtinut]

Well I haves 1995 318ti club sport, 190k on it. Owned it since 1995 with50k on it. Just had the clutch replaced 2k ago. I have noticed that when the engine is cold in the morn and when I leave work that there is a real lack of power especially around 2000 to 3000 rpm. Feels like a flat spot in the power. I have also been getting a squeal/sleek noise. I though maybe that the engine was pinging. It would go away once the engine was warmed up. But when cold it didn't want to rev smoothly through this range. Felt like someone threw an anchor behind the car.
Now two weeks ago I changed the plugs, new bav auto spark plug wires, new valve cover gaskets. Seemed to run a little better but not for long. Then last week I put in a new O2 sensor and upgraded BMW transmission from bimmerbum. The only change now is that when I rev the engine I get a ba vibration from 2500 to 3000. I can feel the engine vibrations more in the cabin as well. Still have the flat spot in the power.

Suggestions??