Sorry for late reply. Bought the car about 8K miles ago. Used Stanadyne Performance Formula immediately after purchase and eliminated smoking especially if I floor it on take off. I honestly did not think the performance difference was that much. Well, may be that was because of the dirty filters I had because I had to change filters about 4k miles ago, including air filter when I started having performance problems (lack of acceleration). That's when I also switched to PS because it's easier to find. Car was faster than it was when I bought it but I thought that was because of the cleaner filters.

I am not talking of a big problem here but I can tell the engine is working harder and rougher than before.

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1981 300SD 118K
2000 Toyata Tundra 64K