48 cj2a, L head motor. The engine was rebuilt, plenty of oil pressure. No leaks except the rear main. 12 volt conversion with gm alternator. New solex carb with fuel pressure regulator set at 2 psi. I'm pretty sure the timing is correct, I set it before installing the engine and checked it with an adjustable timing light. The heat riser appears to be functioning properly. The crossover tub is hooked to the carb and the dipstick breather, but no the air filter. PCV is new and hooked up. The engine doesn't want to idle. With the choke on, it starts right up, but no matter how warm it gets, I can't take the choke off without it dieing. 1,600 rpm is about the lowest it will run. I'm only able to take the choke off if I hold the throttle open enough to stay at the high rpm, any lower and it just shuts off. The propane trick to look for a vacuum leaks wont work because the fan is blowing too much air past the engine. There's only two gaskets anyway, but the intake could be cracked somewhere out of sight. I'm out of ideas. What should I look at next?