Hi and thanks in advanced for looking 
I have a 98 GT, 104,000 miles on it. The problem that I'm having is that originally the car was like puttering on the highway. We tried a used coil pack the first time and it still did the same problem. I drove the car for a month and tried another coil pack and it seemed to solve the problem for abit. About a month ago, I started to smell gas fumes, so the first thing that came to mind was the cat. I look under the cat and saw a leak, also when I reved the car I could hear some rumbling.
So about 2-3 weeks ago I changed the cat. Problem still persist where it stumbles and I once in a while smell gas fumes. So I decided to change the oil, fuel filter and pcv valve. I accidentally broke the plastic holder for the pcv valve, but when I started to drive it the car felt better. I take it on the highway and it throws a code, and is back to the same problem. I get it checked and its a p0171 error. I decided to change spark plugs and wires. Now when I turn the car on, I can hear my air filter (aftermarket K&N type) suck more air and the car stumbles like it going to turn off. It gets worse when I put the car in the drive position. I checked the firing order, just incase and I tested the coil packs by slowly removing the boots from the packs. Everything seems right, what is wrong? I'm about to blow this car up!
p.s. - Forgot to mention I also changed the oxygen sensor after the cat.
I have a 98 GT, 104,000 miles on it. The problem that I'm having is that originally the car was like puttering on the highway. We tried a used coil pack the first time and it still did the same problem. I drove the car for a month and tried another coil pack and it seemed to solve the problem for abit. About a month ago, I started to smell gas fumes, so the first thing that came to mind was the cat. I look under the cat and saw a leak, also when I reved the car I could hear some rumbling.
So about 2-3 weeks ago I changed the cat. Problem still persist where it stumbles and I once in a while smell gas fumes. So I decided to change the oil, fuel filter and pcv valve. I accidentally broke the plastic holder for the pcv valve, but when I started to drive it the car felt better. I take it on the highway and it throws a code, and is back to the same problem. I get it checked and its a p0171 error. I decided to change spark plugs and wires. Now when I turn the car on, I can hear my air filter (aftermarket K&N type) suck more air and the car stumbles like it going to turn off. It gets worse when I put the car in the drive position. I checked the firing order, just incase and I tested the coil packs by slowly removing the boots from the packs. Everything seems right, what is wrong? I'm about to blow this car up!
p.s. - Forgot to mention I also changed the oxygen sensor after the cat.
