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Discussion Starter · #1 ·
1995 Cougar 4.6 stock

Here is the problem I am having:
When I stomp on the gas, the engine will hang around 2000-3000 rpm like something is "holding it back" and hardly accelerates at all. Then if I let off the gas, and gently reapply, the car acts normal.

My check engine light was on, so I had the codes checked at Autozone and got 171 and (174?) codes, which translates to O2 sensors. A while back I took the car to an exaust place, and they claimed the cats were plugged up, but were not sure if replacing them would solve my problem.
The strange thing is, I know there is supposed to be a sulfur smell with plugged cats, but my car is not producing any smell at all. I know the MAF is not the problem, so what is everyone's opinion?

My second question deals with if I do need to get new cats, I would rather go with aftermarket, not OEM and get rid of the 3rd cat. My requirements are:
1. must have backpressure for low end torque
2. do not want to spend over $500 for new exaust setup

What is the best setup to run, and where can I go buy/order the parts? Getting an exaust shop to do the non-OEM work is not a problem.

Premium Member
3,247 Posts
How do you know it is not the MAF ? Those two codes are for a lean condition.

Have you unplugged the MAF and given it a test drive ?

Your symptoms were similar to mine when my first MAF went.


If you want to check your cats for being clogged, just unbolt them at the exhaust manifold, and put a spacer in there, do that there is about a 1/4 " air gap between the exhaust manifold and the flange of the cat. Take it on a quick test drive.
If it runs better that way, you know your cats are clogged.

This is what my Ford Dealer was going to do to check mine. I ended up replacing them myself (with a buddy).
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