I purchaced this car about 2 months ago with 150,000 miles on it. I spent the first few weeks bringing it back up to date on maintenance: new plugs, all new fluids and filters, new motor and trans mounts, new suspension, etc. I also replaced the rubber charge pipe hoses with samco hoses and t bolt clamps. Age and oil leaks had taken their toll on the boost/vac lines and clamps, and they blew off one after another. I replaced them all with new, along with a new PCV valve and diverter valve, and cleaned the ISV and N75. The car ran great for 6 weeks.

Yesterday on the way home from work, I was accelerating away from a toll stop, and at 6000rpm/about 12psi the car gave a big jerk, just like it had a big boost leak. I backed off the throttle, and it ran fine. Now, any time I hit 10 psi it jerks hard like that. I've checked for boost leaks using a tester I made, and there are no leaks. Any ideas?? Output tests are good, all clamps and connections are good, no codes present.