loop does not iterate over list

I want to append in an output-list every letter or letter sequence that are in list (for sequence letter, I replace with 0 incoming elements so that it can be ignored).
What I do not understand is why my loop is not iterating correctly through the list, it only finds one occurence of "okj".

s = "okjokjokj"
l = []
for i in s:
    l.append(i)

dico = ["a", "bc", "okj"]
output = []

for i in l:
    if i + l[l.index(i)+1] + l[l.index(i)+2] in dico:
        print (i+l[l.index(i)+1]+l[l.index(i)+2], "found")
        output.append(i + l[l.index(i)+1] + l[l.index(i)+2])
        l[l.index(i)+1] = "0"
        l[l.index(i)+2] = "0"
        print(l)
    if i + l[l.index(i)+1] in dico:
        print (i+l[l.index(i)+1], "found")
        output.append(i + l[l.index(i)+1])
        l[l.index(i)+1] = "0"
        print(l)
    if i in dico:
        print (i, "found")
        output.append(i)
        print(l)
    if i == "0":
        print ("nothing found")
        print (l)

print("n output is", output)

output is :

okj found
['o', '0', '0', 'o', 'k', 'j', 'o', 'k', 'j']
nothing found
['o', '0', '0', 'o', 'k', 'j', 'o', 'k', 'j']
nothing found
['o', '0', '0', 'o', 'k', 'j', 'o', 'k', 'j']

 output is ['okj']