1993 940 w/275K. Was running fine but had an exhaust leak around one of the exhaust ports, between the head and manfifold. Replaced all 4 exhaust manifold gaskets between the head and manifold, and replaced the gasket between the manifold and down pipe. Can't find any leaks now, and the exhaust coming out of the tailpipe blows strong, so I also don't think there are any blockages in the exhaust. The problem now is that the car idles erratically after startup, has poor acceleration, and produces engine code 1-3-3 (TPS). This didn't start until after I replaced the exhaust gaskets. I've cleared the engine code multiple times, and it comes back. A couple of times early on it also produced engine code 1-3-1 (O2), but the last few times it's only been 1-3-3. I tested the Throttle Position Sensor, and it seems to be working fine. I also ran the various diagnostic tests from the ODB, and everything seemed to be working.