Hello all, I'm a newbie on this site. I just bought my first jeep, a 94 YJ 2.5 manual trans. It was running like crap and got the following codes 12, 17(low coolant temp), 33( A/C clutch), 51(running lean), 55. I don't have A/C. I changed the O2 sensor, no change. So I replaced the fuel filter..no change. So I replaced the fuel pump and saw parts of an old gasket in the tank that was sucked up to the fuel strainer. Removed the pieces and replaced the pump. Runs much better but is getting horrible mpg...like 10mpg maybe. I did a fuel pressure test and pressure was good (31psi) at idle for about 45 seconds. Then it started climbing up to 70psi. I now get the 52 code (Rich running condition). So it went from lean to rich after changing the fuel pump. I haven't changed the thermostat yet. Could that be making the engine use more fuel to try to get engine up to operating temp? It normally runs at 155 degrees which I know is too cold. I have also heard about pinched fuel lines above the tank, and blocked fuel return line causing rich running conditions. What about the regulator? Just not sure where to start and I don't want throw parts at it anymore. Please help!!! Thank you.