I have a Honda civic 1.5 si hatchback 92 k reg. I had a second hand engine put in a year ago and this is when the problem started, the engine will sometimes cut off when slowing down or stopping. The car is jerking in first and second gear, third gear is not so bad. It has trouble reaching 40-50mph. No one Knows what the problem with it is.
I have had the ECT switch changed the timing belt, spark plugs, leeds, coolant sensor and the map sensor changed and none of these have made a difference even though I was told they would. The problem is still there. Can you help?":confused:

Reading sections A and B should help you solve the problem:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-honda-civics-46563.html

Because of the age of the Civic, I would replace the igniter, coil, rotor, and distributor cap. It wouldn't surprise me if the igniter or coil was the culprit, which Autozone will test for free.

This is bad rings. I have a follow up question, does the problem come back and then cause you to go back through your gears? to the point you are doing 20 mph in first.

Yes that is what happens. I have to down gear to get a smother ride and build up my power again.

Piston rings. You can get a little more life out of your engine before rebuilding it by switching to a higher viscosity oil. If you are using 10w/30 consider using a blend of 10w/30 and 10w/40 or use straight 10w/40. This will postpone the inevitable, it won't fix the problem