87 Camaro 5.0 TPI starts and runs fine. Drive for an hour, get into rush hour traffic and it acts like it is only running on three or four cylinders. If I push in the clutch, shut it down and restart it it seems to run fine. Usually it is associated with a pretty aggressive take off and run hard for the first few minutes (it is after all a Z-28, why not drive it like it was designed!) Any ideas?