Hello, My 1999 Chevrolet Suburban with almost 201,000 miles lately it's been running really sluggish. It seems to be kinda rough and it sounds like its getting louder. But its a tank! I don't know what route to take. I know it probably needs a tune up it hasn't been done in like 6 or 7 years but it hasn't had any misfires or anything. No check engine light. No indicators that anythings wrong. Oil is still good. I don't know what to do? I called the mechanic he suggested a air intake cleaning? I've kinda thought about seafoam but I just need help!! Any advice would be great!! Thanks!

 

Get the tune up and clean out your throttle body.

 

I would check the fuel pressure,the cats could be clogged but see how it responds to a tune up with OEM parts these engines seem to hate aftermarket stuff

 

A personal opinion here, but I hate seafoam and the other corrosives. I find it eats seals and gaskets whenever I use it, but some other folks swear by the stuff.

Were this my vehicle, I would go with the advice above, start simple with a tune-up and then go from there.

 

I just replaced my mass airflow sensor and it really brought back the horsepower. It also could be your cats are clogged. Are you hearing a rattling noise under your vehicle. That might be the cats going out. Took my farm truck suburban To Oreilys and they scanned and said cats were bad. Remember even if they are operating with a decrease of 5 percent they can say to replace them.