1999 Dodge Caravan Ticking, engine light on, then off, then

Hello, we left our beloved van to sit for a week at the airport with no known problems. When we picked it up there was a noticeably loud ticking from the engine. We found that the oil was very low, and refilled it. A few days later, the "Service Engine Soon" light came on, and the ticking was more pronounced with acceleration; almost nonexistent when idle. The next day, no more ticking and the light went off. Great, right? That night (last night), pulling into our long drive, I was unable to move forward without pressing hard on the gas, and felt resistance (NO, my e-brake was not engaged!). The car wouldn't move in drive - almost like the brakes were engaged. This morning we drove about 35 miles with no problems, no resistance, no ticking, no lights. After parking about an hour, I restarted engine and sat idling to run a/c for about 1/2 an hour. When I tried to back out of my spot, the car was resisting again. I checked the brakes, pumped them, etc. I also moved gear shift from gear to gear. When I drove out, the resistance became stronger the further I drove. About a 1/2 mile out, I could barely move. The only way I can describe it is a feeling of tension - pressing so hard on the gas and revving but not moving much - and if I pressed too hard it would snap. Needless to say, we towed it out. ANY suggestions are SO appreciated. Thanks! I promise to donate next time - I am so broke today.