Hey all,
Having some weird problems with my EF fairmont that have all happened at the same time, thinking that are all related to a single problem.

I have low vacuum when in gear only, 18 in/hg in P and N, but only 8 in/hg when in D
Because of the low vacuum engine thinks it's under load, so when going from D to R, car gives a massive jolt. And when going back into P revs rise to about 1800rpm then fall to normal.

There is also a massive delay in throttle response when full throttle is applied.
Usually is extremely responsive and will rev pretty much instantly, but now, whether stomping on it from a stand still or stomping on it while cruising, there is around a 2 second delay while the revs rise slowly to about 2500rpm and then it revs hard and fast just like normal after that.

I've tried searching everything I can think of but can't find any threads with the same symptoms I have.

Any advice or input is greatly appreciated!

Also when stalling up to launch off the line, will only stall to 1000rpm and won't go any higher, won't even break traction. It's really frustrating because once it reaches around 2500rpm, it really gets going, the problem seems to be in the lower revs.

Check your timing.

This may be a long shot. But it sounds like your torque convertor is trying to lock up any time the transmission is in gear, instead of just at cruise in 3 and 4 - so you would be getting basically full load from idle, and no torque multiplication. When you are up to speed, can you feel the torque converter lock up around 80-90 kmh in 4th? If not, it is probably already locked up. That could be a converter problem or an ECU problem.

But I can't think of anything else that would put that much load on the engine at idle in gear. It's not a problem with suddenly getting more air when you put it in gear, as it would inject more fuel and revs would rise to TC stall rpm. Besides, what could even do that?

Anyway, FWIW.