why would it no be
would the ECU cause misfiring
There are a number of reasons why a 2001 Toyota Corolla 1.4 GS engine would misfire. Coils are one common cause. Another common cause is the fuel delivery system.
Typically when the engine misfires it will feel like jerking. Find out why the engine is misfiring; run a computer diagnostic test and the computer should reveal the answer.
a plug misfiring would cause the rough idle and check engine light or if u changed the plugs and wires u could have put the plug wires in the wrong order
A faulty ignition coil or module can cause misfiring.
sounds like your engine needs a valve job worn piston rings would also cause low compression ,but not cause the backfireing
That would be an engine cylinder misfire , but either more than one or it can't determine which engine cylinder is misfiring
Things to check: Distributor cap, Plug wires, spark plugs, Ignition coil. On that year this is the most common things that would cause an engine missfire.
It's probably misfiring. You would need to diagnose why.
The year, make and engine info would help but, a vacuum leak could cause that.
1. Engine Idle speed set too low? 2. One or more cylinders misfiring at low idle? (Spark plugs, plug wires, distributor cap or distributor rotor would be the common culprits.)