Recently I had a problem where my engine was turning off randomly while driving. There was no noise or warning it would just suddenly be off. The first few times it turned on without a problem. After a while it wouldn't turn on anymore. After some investigation it turned out that the fuel pump was bad (took it out and had it tested). I replaced it and now the car runs great. The only problem is when I turn the AC on the RPMs drop to almost 0 and the car starts to chug like its going to turn off. I did not have this problem before the fuel pump. The car did, however, sometimes fluctuate a little in RPMs while idling but not nearly this bad. Any ideas or suggestions?