Originally Posted By: clinebarger
Remove the booster hose from the intake manifold, plug the port & retest....Be careful as you will NOT have brake assist!!
Did this after doing the test below. There is a slight improvement but the chug is still felt. RPM still drops when pressing the brake.
Originally Posted By: clinebarger
If your running at speed....Applying the brakes will unlock the torque converter.
Trying idling at a stop light with the parking brake instead of the service brakes & see if it improves.
Did this. It does improve. The rpm drops when you press the brake and hold - this made me think it was the booster or check valve. By the tach, it drops to 500rpm, idle is 750 according to my shop manual.
Originally Posted By: clinebarger
A scan tool would help you see if the actual idle speed is lower than the target idle speed. I would also take a closer look at the old mount that looks good!
Take a floor jack with a thick piece of rubber & take the weight off that mount & see if the vibrations go away.
Mounts can visually appear OK but be collapsed internally, Does the engine torque on this mount in drive??
The motor visibly moves when in gear. I probably should just replace the passenger side mount. (Supposedly it is fluid filled and leaks when it goes bad. I did have an oil leak from a loose filter cover - so I may have missed the leaking fluid.) Long story short, aligning the transmission mount was tougher than expected, and I stripped a bolt - which needed a helicoil, and a trip to junkyard to find replacement bolt. Learning experience, but I'm hesitant to work on the last mount (which is on the other side of the motor) until I'm sure I fixed the cause.
I really do appreciate the help. I think I'll pick up the scan tool and confirm the RPM changes again at temp.