2001 Ford Taurus 92000 miles

2001 Ford Taurus 92000 miles. I appologize but this is going to be a long one. A few months ago the check engine light came on and when the code was checked it was p1401 autozone said it was something to do with the egr system, but that if it was not causing any problems it could probably wait a while before getting fixed. I had no apparent problems for 2 months but kept checking the code once a week to make sure nothing else came up. 1 month ago it began running very rough. I changed the Plugs, plug wires and was told there was no actual distributor cap and rotor that it was linked to a computer module. It ran fine for a day and began missing again when checking the code it said it was misfiring in the first cylinder. One of the wires had come loose. It continued to run a little rough so I went ahead and changed the egr valve pressure sensor. After changing that the light came on and said the throttle was less than expected and it was acting a little bogged down. It also started making a really bad squealing coming from the pulley system, and the air conditioner stopped working. I changed the throttle pressure sensor because I had dropped it when changing the egr sensor, and the code for the throttle went off but while doing the driving part of the computer reset the rpm began jumping and the check engine light came back on. This time when checking the codes it comes up p1633 which the parts store says they have no information on. Any ideas on what to do next?