I have a Rng Rvr 88 When i driving a lot of time the automatic trnsmission loss power 3 weeks ago changed oil and filter but doesn´t work

No,the cat is not the problem,removed mine,got more power and better gas mileage,what size engine do you have,when was the last time you changed the fuel filter.

You have three options,
(1) Buy a new motor.
(2) Buy a good second hand motor.
(3) Get your motor reconditioned.

You sure filter is facing flow correctly?:I'd check that first,some cars/trucks have in-line filters.

The following are the general instructions on the start of diagnosing any electronically controlled engine or transmission problem.

The engine and the automatic transmission (transmission control is only for automatics, engine is still computer controlled no matter the transmission type) in this vehicle are computer controlled and in most cases when a fault occurs a fault code is stored in the memory of the computer control module. There are exception to this, such as the Mass Airflow Meter and fuel pressure problems. What must be done is to have all the basic testing done such as a scan of the system for fault codes as well as a check with a live data scanner tool for engine functions that are not within range of normal, a trained technician is required to know what is correct and what isn't, then based on careful diagnostics done from a factory repair manual the correct part is replaced or the wiring repaired or the computer replaced (known as the PCM), which is very rarely the problem. Other basic checks must be done as well such as mechanical problems with the engine as well as engine state of tune and mileage on the engine. The transmission can have mechanical issues as well such as no gear engagement at all or a failed pump or other pressure related problems. Also engine mechanical problems ca cause many drive-ability related problem such as rough idle and other symptoms

check your plug wires I had same problem, turned out to be a bad wire.

check transmission fluid.change fuel filter and air filter.try changing up on where you buy gas .because bad gas causes problems.

i think you transmission is slipping you should get it checked out or u can do a tranmission kit change the filter and oil

if it needs changing you should get the bands serviced and get them to do it why do have the job

How much oil is left inside the engine? Are there signs of oil loss under the car? is the drain plug tight and does it have the gasket in place? How about the filter?
None of these things will make your engine better,. but will give you the "why" it happened answer...the rest is up to you!!!

Oil pressure switch maybe bad, replace it no chatter in motor?