Could be. Have the LIM gaskets ever been changed? Also, the plastic UIM have been known to crack and cause issues. I had one crack around one of the bolts and cause a slight leak. It still ran, but the leak was obvious in the way it ran.
You could use brake cleaner but its a bit more harsh on paint if you overspray. As long as you aren't soaking the motor in carb cleaner or spraying the exhaust mani's directly you should be fine. Might be best to do it when the motor is cold at first startup. Just a small spray here and there will be all you need. No need to empty the can, lol... Oh, and might want to wear safety glasses just in case it hits something and comes back at you. Life lesson you don't need to have.
