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Discussion Starter · #1 ·
ok I geuss it's been a gradual thing but my 5.3 now seems to be pretty guttless and getting horrible gas milage I do the fuel filter often and do fuel injector cleaner every oil change it also has ams oil xps 7500 synthetic in it any sugestions?
 

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Discussion Starter · #5 ·
this is a better place isn't it. it's got 3:73's but it used to be fine with the 35's and it's on 33's for the road right now and it's got 77000 km's and it's defentaly lost power
 

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Yeah it could probably use a tuneup. Couple of things to check:

Is the temp guage in the same place it has always been? If its colder you may have a stuck-open thermostat, which won't let the engine warm up fully.

How old are the spark plugs? If they're new they might need replacing, don't forget to gap them correctly.

I'd also get it regeared, 3.73's and 36's is hell on your tranny.

also are you getting a service engine soon light?
 
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