THE CAR: 1989 744 GL with Bosch LH 2.4 and 230k miles, auto.

THE PROBLEM: Intermittently, it will just bog, engine will not rev, very slight hint of backfire/misfire while accelerating from a dead stop. It also cracks, once in a while, like it is backfiring through the intake. To test it, I sometimes do a brake stand to see what it will rev to under the load - its an NA so it never spins the tires - but if its "acting up" it will do like 1400 RPM and miss, if its being normal, it will rev to 2000 RPM and grunt.

Its almost like something will click (no clicking noise, however) and it will accelerate with full power after the bogging, which can last for 4-15 seconds under normal acceleration.

It also acts up occasionally while accelerating slowly (not causing a downshift), at other speeds like 50 or 60 mph.

It will idle okay after the ECU is reset (I have just fixed some vacuum leaks). I can't say how it will idle once it re-learns in the absence of vacuum leaks. I am also curious to see if it will learn around the hesistation.

WHAT I'VE DONE:
With the low air-flow conditions it really seems like it would be the AMM, but I have swapped another in and no change. I have removed the knock sensor from the block and tried to accelerate (while keeping the RPM under 3000 to prevent the check engine light). Again, vacuum leaks taken care of - new intake gasket, TB gasket, fuel injector o-rings and cleaned TB. I want to drive around with a fuel pressure gauge hooked up to make sure the fuel pressure regulator isn't lazy or the fuel pump for that matter. In the diagnostic mode in OBD-I, LH sees the throttle open via the TPS, and it also clicks. New 02 sensor, AMM was cleaned a couple months ago.

Any ideas?

I want to recheck and see if this condition happens with the AMM disconnected and maybe the wiring to the AMM.

Thanks,
Smith