Hello. 1995ish Mercury 40hp 4cyl. Sat for 2 years. Took out today. Stream would be perfect at warm up, then just slowly stop over a 1-2 minute span. Shut down, let cool down... same thing over and over. Tried idle, half throttle, etc. always same thing. Would pee perfect and just gradually go to a trickle to steam to nothing. Please advise. Thank you