The filter I changed is in the line just before the carb.
I am down to about 1/4 tank of the '93 octane, and will refill with '87 to confirm the fuel difference, but I am pretty sure it made a difference, unless there is some other variable I overlooked.
When I try to push it past the cough, it gets worse. If I do push it like that, it gets so bad I need to take it down to an idle to bring it back. Otherwise it gets better as soon as I back off.
Remember that the truck had overheated badly a few times last month - I have been worried that it might be partially blown head gasket? The oil and coolant look fine.
