can someone help?

i have a legacy 1992 turbo

every now and then the boost starts to come in and then it drops to almost nothing (about .5 bar)if i stop and disconnect the battery it will come back again straight away bt if i keep driving it without doing the battery the car will run sick with no boost until it decides to pick up again (can't give a time on how long it takes to come back it)

Any help please..........

 

hi quadman

i have a 97 uk turbo...on full boost my boost gauge reads 8-9PSI which is around 0.5bar....does this mean i'm running low boost?

 

whoops...... my fault

i should have put .5 psi