i have had a problem with my high rpms for over a year now and i cant figure it out. my vacuum lines have already been redone, i have recently had my lower intake gasket replaced. on full throttle, i get good boost(10-12psi) up until around 4500to 5000 rpms where my motor will begin to sound really raspy and as soon as i shift and get back on the gas the boost wont come back unless i let the rpms fall a little and then step on the gas again. also, just recently my idol has been jumping around. even after it is warmed up, when i slow to a stop sign and throw the tranny in neutral my idol will jump around between 1100 to 1400 rpms for a couple of seconds and then return to a steady 1200-1400 rpm idol. if anybody can help me with my problems i would appreciate it very much. do you think i may have a intake leak, maybe the crossover pipe from the y-pipe or bad throttle body gaskets. thanx

 

For your boost problem, the first thing to check is your check valves. A bad check valve will lose the vacuum and when you release the gas it build more vaccuum then when you hit the gas the boost comes back on. Hope I made sense

 

that made sense. i'll check those and let you know how that works out. thanks