Help Me Pleasse

Hello All,

Im new here and im having all kinds of issues with my 03 ford focus wagon. 130k. the CEL has been coming on and off for over a year now and its been something to do with the EGR valve. everytime I am at autozone I get the code read and its always comes up with the same thing... EGR valve, its always ran fine, no problems at all. so recently I have noticed its running really rough, not idleing rough but running. when I pop it out of park into reverse it starts to rumble like its almost about to stall (it has stalled a few times but not in recent weeks). Then when at highway speeds 45 mph+ it will sometimes rumble as if its having problems shifting or something, just feels really rough. Then yesterday I was on the highway going maybe 70+mph and the engine light started flashing which it turns out means my engine is misfiring. So I did some reading and found that the EGR is likely the problem, (duhhh should have done something 11 months ago). So I pulled the EGR valve and EGR tube off, check them out. no crud or crazy ammounts of carbon build up, from what I can see there is good actuation of valve (from pushing on bottom with small screwdriver, not actually applying vacuum. I reassemble everything. its still doing it, so I plugged the vacuum hose going to the EGR valve. this is supposed to not allow the valve to open and if it fixes the problem then it is likely the sensor instead of the valve. well the rumbling was much worst when the hose was plugged. I didnt take it for a full out test drive with the vacuum hose plugged just reverse and forward about 25 feet but it was noticably worst. Is this an EGR sensor or EGR valve issue? I would like to buy the correct component the first time out because frankly I dont have enough money for both. Thanks in advance for your help.