can ethanol cause roughness?

[whatnot]

'66 911

Just had the engine rebuilt. My mechanic filled the car with 93 octane/ethanol. It's running like it runs on 3 cyls, then 4 cyls. then 3 cyls. etc.


It was doing this before the rebuild. We cleaned out the jets, put new fuel filters on it (actually even added one) and then I began using pure gas (87 octane). It ran great for several thousand miles like this.

But now....it's back. I personally believe it's the gas. I believe the ethanol is clogging the jets. When the jets are cleaned out, it runs good. But only for a little while. Then it starts doing it again and the jets have to be pulled and cleaned and reinstalled. This makes the car run good again for another little while.

My mechanic insists it's not the gas. He says the shaft that runs through the carbs....the bushing that the shaft runs through is worn, causing air to enter there and run lean. The shaft does move ever so slightly.....however.....it did before and ran just fine.

He's calling for rebuilt carbs. I'm no mechanic. But it seems to me like....if the carbs needed rebuilt....blowing out the jets would not make the engine run smooth and good.

I think the car would run good again with regular, pure gasoline.

Thoughts if any...thanks..

EDIT: The reason I ask is.....I was going to drive the car to Florida tomorrow. I just filled it up with high octane/ethanol and it's running badly. I can't take off to florida hoping the car smooths out by running pure gas and blowing out the jets. I gotta know it's right before I head out. Driving it like this for 2000 miles....I'm afraid it'll hurt the engine.