99 Passport IMG every two years!

I have a 99 Passport with 166,000 miles. Have had the PO 171 and 174 codes show up with replacement of lower intake manifold gaskets first in 2003, then 05 and 07. Today went in for oil change and investigation of recent check engine lite to find out that same codes and diagnosis is coming up. Why are these failing so often? I know this is a problem with the Passport but this often? Are there other things that could be causing this? Thanks for your help as I don't know how much more $ I should put into this car.

Isuzu changed the torque specs 3 times on it due to breaking isssues. Has isuzu been the one changing it or some other shop?

I had mine replaced 2x in 75k.

An independent shop has done it all three times. First at 83,000, then at 132, then 155 and now same problems at 166. Nice to know that Isuzu is aware of the breakage. Where would I find the torque specs for the mechanic as he may not be as motivated as me!! Or do I pay the big bucks and go to a dealer! Thanks for your help.

The latest torque spec is 13 ft lbs. Also make sure they use an inch lb wrench instead of ft lbs. Most ft lb wrenches wont be nearly accurate enough at that low of a setting no matter how well calibrated they are. Tell them 156 inch lbs (which is 13 ft lbs) just to be sure.

Thanks Dave for the precise info. I will bring it to my mechanic.