Another update, ok after replacing the leaking vacuum modulator the vacuum in the whole system is now very stable. Off the mainline I'm pulling 22.5 Hg of mercury and at the inlet of the vacuum amplifier I'm pulling 16 HG of mercury and at the outlet to the trans modulator, I'm pulling 6 HG of mercury. I don't know what the optimum vacuum to the modulator should be at idle, but at full throttle, it should be 0 for maximum hydraulic pressure.

After fixing the modulator and test driving the car I found I have third gear back however third gear does not pull very strong like second gear, it will engage but I can rev the engine up a lot and it will barely accelerate. I also tried unplugging the kick switch and that did not help, My next step is to hook up vacuum gauges and look at the vacuum while driving down the road, if vacuum checks out then I need to check hydraulic pressure in the trans before I rule out there is something clogged in the valve body.

Also, something interesting to note is that while driving today and yesterday my antilock brake light came on for thirty seconds and then turned off and the ABS has never worked on this car since the wheel speed sensors are bad supposedly. To sum up the new shifting issue, the car will shift into third and will not lurch anymore, but it will only lightly pull in third gear at 20mph, I can floor the car and it will barely accelerate, more diagnosis is required. I also need to flush the fluid in the trans again to get more of the pinkish transmission fluid out.

Could someone send me the vacuum diagram for a 1985 300sd with federalized emissions? (Not the California model) I need to trace out some more vacuum leaks and I also need to make sure the vacuum lines are routed properly in the system. I'm trying to make sure the vacuum system is working properly and providing the correct vacuum to the modulator and VCV before I do any transmission adjustments.