I have to spray starter fluid to get it started and when I hold my foot about half way down it runs and sounds great but if I just hold it there it will decrease rpms and stall after just a few minutes. I'm trying to remove the alda because it can't be adjusted, but I can't get the alda to break loose of the big nut under it. The big nut will turn but it is attached inside to a spring or something. Any suggestions on how to get the thing off or maybe what else could be causeing the problem. Thanks for your help.

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83 300SD
80 300D