1998 Ford Taurus SE milage:183100 engine size:3.0

I have a 1998 Ford Taurus SE. Although when the VIN is entered into a computer at a parts shop it comes up as a GL? Anyway. Here is my major problem right now. I went to work at 5:30 am and had no problems. It wasn't until after I got off work in the afternoon when I went to go home I got maybe 2 blocks away when my car started acting like it was out of gas and would chug. I couldn't get it to go more than 20 mph if I was lucky and it would continue to chug and gasp and can even here some popping going on comming from the intake to the breather. I put it on a computer at the parts store and it said the cam sensor was bad. So I replaced that. I put it back on the computer and now it says its running lean. It also flashes the CAT, EVA, & PVR codes. I have been able to get it to run up to 40mph, but it still chugs, gasps & pops. I am a single mom with limited funds and can't afford to keep putting money into something that might be the problem, and turns out it doesn't fix the problem. Can anyone tell me where I need to focus my attention on and what else I can do? Or better yet. Does anyone KNOW what the problem is. Your help would be greatly appreciated.

Sandy From South Dakota