Idle problem low vacum

Manafold vacum tests

Hi Gary, welcome to the forum, I’m not sure what the point of your post is? Can you elaborate slightly?

'97 - xj16-intake manafold best source for reading. Should be at xx … been an excellent auto with 225,000+ miles.
Starts fine, 25 seconds into rough idle. Had injectors serviced (first time). Plugs & coils replaced were due…
Also had spare TPS exchanged.
All suggestions/tests appreciated… note, my third jag past 20+ yrs🤘

Check carbon build up on the back of your throttle body plate
It cakes up and won’t close the butterfly giving you a stumble
Good luck
225,000 miles is just breaking in an x300

Checked/clean, first cleaning at 90,000… have also replaced IAC… And found its connection to intake manifold plugged/cleaned etc. NO CHANGE (lost $1.00bet)
To try to do proper manafold vacum test. Only connection I found was source for brake booster, right? Should read ??.
It’s a bad idle after 30 sec start & really not able to drive, will rev up / and die when stopped. Many thanks for ideas.

It is a virgin
Time for a compression check?

Not really a virgin – this gal has many miles to go with its excellent compression.

Have you tried spraying starter fluid around the intake manifold to see if there is a leak?

Yes, that’s got me going as it smooth out for a bit. Will post pic etc what I did etc. Later. So going to do another vacum test with assistant (?)… only placement for tube/connect to manifold that I see is the small tube for brake booster, right?
I have another theory will note to all later. Got to go

So the engine responded to the starter fluid sprayed around the inlet manifold? Replace the gasket would be my thought then.

I was having fun with you…