vaccum test

is there any cheap way to rig up a vaccum test at home? im having a lot of trouble with my car, keeps getting PO171 and PO441 and i took it to the dealer and they said the supercharger gasket was leaking and for a couple hundred $$$$$ they'd fix it! so my bf replaced it (after just replacing it with the head gaskets!) and im still getting the same codes and when its idling it feels like it wants to die but never actually does and it doesnt have much power. autozone first told me to replace the purge valve and that didnt help either......does anyone else have any cheap ideas? im running out of money and luck! thanks
oh its a 97 gtp with 150k
and i dont know how old the 02 sensors are but at az they told me that they'd be bad if a certain code came up WITH one of the existing ones that didnt, so that rules that out too right?!

i'd wanna look towards the EGR valve if you've already replaced head gaskets and the supercharger gasket, mabye the look at the LIM gaskets

we already did the intake gaskets too with the head gaskets

p0171- oxygen sensor detects lean condition
p0441- evaporative emissions incorrect purge flow

A cracked, broken or disconnected vacuum line could cause both codes, so I'd look at all the underhood vacuum lines for damage. When he did the head gaskets, did he use good quality gaskets to do the job and torque everything to spec with a good quality torque wrench? If all the vacuum lines check out, spray wd-40 or carb cleaner (be careful to keep it off hot exhaust manifolds) around the throttle body mounting area, lower intake, etc... If the idle changes when you spray an area, you have a vacuum leak there.

yeah i got a garlock gasket from zzperformance
thanks that should help.....for now!!!!!

Sounds like a vacuum problem to me but it could be further back at the gas tank (pressure sensor or leaking fuel pump pod o-ring) and evaporative charcoal cannister, etc. The easiest and most inexpensive way to check engine vacuum is to hook up an automotive vacuum gauge (0 - 30 hg). Cost is around $25.00. Tee into the vacuum line going to the purge valve from the throtle body and see if it reads at least 15 - 22 in-hg at idle. That way you could rule out an intake gasket causing the problem or something done wrong during the work performed. Since you have a L67 GTP also check MAP vacuum which is different from regular engine vacuum.