According to you, they added doctrine? OK.

Who is Iggy? LOL…
The ECF’s led me to the Catholic Church. Examples of the ECFs promoting liturgical Protestantism?
Is it safe to say that Ignatius of Antioch belonged to the 1st-century Catholic Church, which is the present-day Catholic Church, although altered doctrinally speaking, as per your belief? “Wherever the Bishop appears, there let the multitude of the people be; just as where Christ Jesus is, there is the catholic church”?
The ECF’s led me to the Catholic Church. Examples of the ECFs promoting liturgical Protestantism?
Sure. Here is Mathetes re. Substitution.
But when our wickedness had reached its height, and it had been clearly shown that its reward, punishment and death, was impending over us; and when the time had come which God had before appointed for manifesting His own kindness and power, how the one love of God, through exceeding regard for men, did not regard us with hatred, nor thrust us away, nor remember our iniquity against us, but showed great long-suffering, and bore with us, He Himself took on Him the burden of our iniquities, He gave His own Son as a ransom for us, the holy One for transgressors, the blameless One for the wicked, the righteous One for the unrighteous, the incorruptible One for the corruptible, the immortal One for them that are mortal. For what other thing was capable of covering our sins than His righteousness? By what other one was it possible that we, the wicked and ungodly, could be justified, than by the only Son of God? O sweet exchange! O unsearchable operation! O benefits surpassing all expectation! that the wickedness of many should be hid in a single righteous One, and that the righteousness of One should justify many transgressors!
Mathetes to Diognetes chapter 9, Schaff, Philip. The Ante-Nicene Fathers. electronic ed. Garland, TX: Galaxie Software, 2000.
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Also Chrysostom clearly speaks against the bishop or Rome or Peter himself being the ruler over the entire Church.
He speaks of the bishop of Antioch, referring to him as another Peter. Where all bishops have the authority of Peter.
In speaking of S. Peter, the recollection of another Peter has come to me, the common father and teacher, who has inherited his prowess, and also obtained his chair. For this is the one great privilege of our city, Antioch, that it received the leader of the apostles as its teacher in the beginning. For it was right that she who was first adorned with the name of Christians, before the whole world, should receive the first of the apostles as her pastor. But though we received him as teacher, we did not retain him to the end, but gave him up to royal Rome. Or rather we did retain him to the end, for though we do not retain the body of Peter, we do retain the faith of Peter, and retaining the faith of Peter we have Peter (On the Inscription of the Acts, II. Cited by E. Giles, Documents Illustrating Papal Authority (London: SPCK, 1952), p. 168. Cf. Chapman, Studies on the Early Papacy, p. 96).
In the modern Roman Catholic reckoning, is any other bishop besides the Roman one to be considered “another Peter” or equal to Peter?
I think Chrysostom referred to the bishop of Antioch as another Peter because he was the successor of Peter, AND all bishops and apostles had the keys as possessed by Peter. Observe what he wrote about John.
*“For the son of thunder, the beloved of Christ, the pillar of the Churches throughout the world, who holds the keys of heaven, who drank the cup of Christ, and was baptized with His baptism, who lay upon his Master’s bosom, with much confidence…” (NPNF Vol. XIV, p. 1)
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All apostles and bishops have the keys are can be considered the pillar of the Churches throughout the world, and not the Pope alone.
Read what Chrysostom writes about the Council of Jerusalem:
“This (James) was bishop, as they say, and therefore he speaks last…There was no arrogance in the Church. After Peter Paul speaks, and none silences him: James waits patiently; not starts up (for the next word). Great the orderliness (of the proceedings). No word speaks John here, no word the other Apostles, but held their peace, for James was invested with the chief rule, and think it no hardship. So clean was their soul from love of glory. And after that they had held their peace, James answered. Peter indeed spoke more strongly, but James here more mildly; for thus it behooves one in high authority, to leave what is unpleasant for others to say, while he himself appears in the milder part…” (NPNF Vol. XI, p. 205, 207)
I thought according to Catholic apologists Peter had the “chief rule” even at the Jerusalem council?
There are many more in fact the Didache charges Christian congregations to appoint for themselves honorable bishops. Just as Protestants do today.
*Therefore, appoint for yourselves bishops and deacons worthy of the Lord, men meek, and not lovers of money, 1 Timothy 3:4 and truthful and proven; for they also render to you the service of prophets and teachers. Despise them not therefore, for they are your honoured ones, together with the prophets and teachers. And reprove one another, not in anger, but in peace, as you have it in the Gospel; Matthew 18:15-17 but to every one that acts amiss against another, let no one speak, nor let him hear anything from you until he repents. But your prayers and alms and all your deeds so do, as you have it in the Gospel of our Lord. Didache 15
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When was the last time a Catholic congregation or diocese appointed its own bishop. When was the last time an individual Catholic had any say at all in who lead them?