My 94 Ranger 2.3L runs fine without the AC on. However, when I turn the AC switch to ON, the engine bogs down and runs rough. At idle, it feels like it is going to stall. At cruising speed, it feels like it is missing. The fuel pressure checks good (38 psi KOEO; 31 psi ER). There were no trouble codes stored in the EEC. Any ideas?