Car building boost before rpm's

[AlwaysBroke]

Hey guys
My 90 TSi AWD 5speed, is suffering from some serious idle issues.
When started the car runs fine at idle in gear or in neutral.
If you rev the engine the boost gauge will go up before the tach goes up and then the car stalls.
Once in gear and moving car runs good, as soon as I come to a stop light though it falls on its face and stalls immediately.
When in gear and moving the boost gauge and tach are normal. Neither one is aftermarket both are stock.
I have run out of ideas, in the last week i replaced the Ics, Tps, Fuel filter, pcv valve, air filter.
I also took it to a shop who couldnt figure it out, they then sent it to a mitsubishi dealer, they didnt know what it was either.
It is getting very expensive and I feel like a moron for not coming here for the answers first, oh well, live and learn i guess.
Oh and I did search extensively but have not found a problem along the lines of this one.

Thanks for any help or suggestions

 

[billdo_83]

Your stock boost guage is worthless. That doesnt tell you your boost at all. If you want to know what your boost is doing then buy an aftermarket gauge that actually Ts into a vacuum line.

It sounds like you may have a vacuum leak though.

 

[AlwaysBroke]

Thanks for the reply, I went ahead and checked all lines and hoses everything was fine, I am hoping to upgrade my guages very soon as well. Could this be an ecu issue?
I have replaced almost everything i could think of except that. Maybe another sensor that I missed? Like i said I replaced the ics and tps. Car has a new Evo III turbo.
It started doing it right after i got it back from having the head rebuilt. Maybe the shop messed up the head?
Any help is greatly appreciated!

Thanks