Corroded Tube (Fuel Related?)

OK tube, pipe and line gurus. Whilst pottering about with my backfiring 88 2.5 I spotted a perished rubber hose half hanging off the nozzle it's supposed to go on. I nudged it off and the whole thing fell apart. I pulled it a little to see what it was and it literally came away in my hand but was obviously connected previously at both ends. Ita about 6 inches long. So I grabbed a new bit if tubing and put it on the nozzle and then looked to see where it originally conneced to at the other end and found a disconnected socket with a weird object on it. I took a chance and connected it and started the Jeep up and no apparent issue. From the pics can you tell me what this line , hose, tube does and from where to where please.? On the pics its the third tube down with the new jubilee clip. This was where it was literally hanging off and totally perished. It's way down behind the valve cover near the firewall in a 2.5 . The other pic is of the strange little device I think it supposed to be connected to. Hope that explains. Many thanks.

Hi, mine is a 1988 built for EU export and has a TBT single point fuel injection system. I plugged the loose end into that thing and I think..... think.....it might have been the root cause of the massive backfire along with a 100% totallycaevon packed EGR valve, solid carbon with no open holes.

bushyeyed1 said:

Sounds like a vacuum line with a one way check valve. I’m not sure about your year YJ since you have carburetors and mine doesn’t

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Thanks! It does seem to be resolved. Did a 70mile trip last night and not a peep from the engine. I'll check out the diag over Xmas and see what I fixed haha. Literally no idea.

Well, I spoke too soon. The backfire on deceleration is back with a vengeance. I changed the Idle Speed Sensor and the MAP sensor and reset the ECU overnight as the Jeep was idling really high, up in the 1500 mark even when warm. Now it runs super low on idle - about 700 - and lower on deceleration emitting a proper explosion out the exhaust. It's fine driving about and no bangs etc, but when I slow down, especially out of gear, it's like the 4th of July! Sooooo frustrating. I tried moving the little screw on the Idle Sensor and it made zero difference. I've checked the Oxy sensor nearest the block and it seems clean enough. Ive replaced all sorts of tubes and hoses and no joy.
Anyone got any advice on a backfire on deceleration and where to start looking for a cure please? 2.5l 1989 with TBT.
Thanks!