Her repetition of IIII is not intentional. She probably is not aware of it. It's just a matter of her little brain processing more complex thoughts faster than she is capable of organizing into her language. This is typical development for her age.
Please don't call attention to it and stop any one else from commenting on it. When she speaks, attend only to what she is communicating , not how it comes out. When she is done speaking, just keep the conversation going.
And finally, this may or might not apply to you, but, it can be helpful to slow down your own rate of speech and shorten your messages, if you find that you naturally speak quickly and in run-on sentences. (Like me!!!) When I would use my natural rate and complexity of language, my child would have many more repetitions. Easy back a bit on my rapid fire and run-on style was quite helpful. (I did not speak slowly or briefly, I just stopped being quite so verbose!) All my best.