94 escort 1.9l engine questions

Hopefully someone can help me out here. I have this 94 escort that I would like to keep but I think the engine is about shot.

It still runs halfway decent, just not alot of power. Knocks a little and shakes a bit at first start-up, but calms down after it warms up. It has approx. 120k miles on it and I'm just wondering at what point would you typically decide to swap the motor. And if I do decide to do that, how difficult of a task is it to swap this motor out yourself, assuming that you have a somewhat knowledgeable person assisting.

Any recommendations on where to get a decent used motor if I do decide to swap it out?

Thanks.

engine swaps on my 91 1.9 was a breeze took about 10 hours to take out 2 engines and put one back in. just buy a manual and it will tell you how to do it. I had over 205,000 on it when I sold it a few weeks ago, still ran good

I just took the engine out of my 95. Two things: sometimes the torque converter likes to stick in the engine crankshaft, if you dont separate them you wont have enough room to pull the engine out cause the front of the engine will not clear the inner fender and you also have to pull the front engine mount off to clear the inner fender also. Those two aside it was pretty straight forward and easy.