Check timing...did not see that on your list...and while doing so...ensure the distributor is working correctly.  When you rev the engine the timing should advance about 30 degrees.
Z

    On Monday, April 19, 2021, 12:04:20 PM MDT, Dan N <dn92610@gmail.com> wrote:  
 
 hi all,

my 89 tintop Syncro has this weird issue that I try to find how to fix...

From standing still in 1st gear the van (empty van) is very unresponsive,
something like it has no power at all, slow moving. If I rev it up to
between 2K rpm to 3K rpm, the power comes up and it moves, like normal as
it should - otherwise once it's running it works fine all gears, no lack of
power.
If I stop, put it in 1st gear then it did the same again, engine cold or
warm it doesn't matter.

I did the followings:
- check vacuum - no leak
- check TPS - it clicks well as it should
- new spark plugs NGK BP6ET
- new dist. cap and rotor
- new fuel pressure regulator
- new fuel filter
- new Temp2 sensor at the thermostat housing.
- new Oxygen sensor at the cat
- air filter is very clean
- put in a spare AFM - and another one - no change
- spark plugs color is grayish, not white and not brown.

The one thing I guess is the valves are not opening/closing correctly (on
one o2 2 cylinders), not checking this yet.

I am lost... Please help if you have any idea.

thanks in advance

thanks in advance