I have an issue with a 87 t2 it would backfire and hesitate under load as if the secondaries was not working. So i started looking for vac leaks or something that poped loose as it just started doing it. Also noted that it was hard to make boost while the problem was present. I noticed a small split in the snorkile pipe going from the mass to the turbo, it looks as if the heat from the turbo had baked the rubber hard and caused a leak. what is a good way to repair this tube. its about 1 inch long split. I have repaired it with tape and rtv but it dosent stay fixed in the heat.

 

Try Mighty Putty. The stuff that Billy Mays hawks on TV. I used it for a similar problem under the RX7's hood. Dries hard as a rock and doesn't seem at all phased by the heat.