Slide intake vac line question

[chokingthemerc]

Anyone able to tell me what should be connected to the middle vac line plug on the top of the slide intake? One line is running to the ECU and the other to the fuel reg. Should it just be plugged off?

2.5 260 EFI

Thanks

[HStream1]

Cap it off.

[Dave Strong]

Could be used on older analog vac TPI.

Dave

[chokingthemerc]

Thanks... Capped it off and cleaned all the lines and fittings. wow, what a difference!

[chokingthemerc]

so i spoke too soon. It idled fantastic. Put it in the drink and as soon as i get on the throttle it starts to rev up and then bogs right down to idle. from idle i can repeat that process time after time. As soon as i take that plug off and leave the line open it revs up fine...... but caps out at about 6-6500 RPM. it pulls very hard through 6k then falls flat. I put in new plugs and took a look at them after a 30 min run and they are all soaked. It looks to me like ECM is stuck in rich mode but i dont know how to confirm that. so far i have;
- replaced all the plugs
- cleaned all the vac lines
- Cleaned harness and ecm plugs
- new rectifier
- new battery
- new regulator

One other strange issue was that occasionally when it hit 6-6500 rpm my guages will randomly stop working (then pick up after a second). Would a weak high side on the stator cause that to happen.

Thanks again for any help / suggestions. New to high perf Mercs and trying to figure it all out.