Car enthusiasts and auto mechanics the world around know the distinct sound of an engine that isn't firing on all cylinders. In much the same way that a coughing engine saps power and performance, Sprint Nextel (NYSE:S) has been knocking and pinging for almost two years now. The good news is that the company's latest earnings report shows there's still an opportunity for a tune-up.  

Sprint Nextel reported earnings of $19 million on revenue of $10.2 billion for the quarter. (Have a glance through last quarter's results, too.) While increased costs ate into the bottom line, however, Sprint Nextel remains cash flow-positive. The $183 million in free cash flow and $1.1 billion the company paid to buy back its own stock show that there is still substantial underlying value in the business.

Wireless metrics indicate that Sprint Nextel has been making tepid progress toward regaining the operational performance that made it the No. 3 carrier in the United States. The company added a net 400,000 subscribers, a fairly weak number that's even weaker when you consider that only 16,000 of these were the more lucrative post-paid subscribers. But it's still far better than the net customer loss reported last quarter. In addition, blended churn (which included both post-paid and pre-paid customers) has shown a marked improvement to 2.5%, below last quarter's 2.7% level.

Top-fuel wireless competitors such as AT&T (NYSE:T), Alltel (NYSE:AT), and Verizon Wireless, a joint venture of Verizon Communications (NYSE:VZ) and Vodafone (NYSE:VOD), continue to leave the lumbering Sprint Nextel in the dust. Sprint Nextel's tortoise will likely trail the hares for some time.

More than anything, Sprint Nextel needs time -- and money. The company is investing heavily in network improvements and in its new WiMax network, on which it spent $51 million this quarter. Sharing some of the WiMax cost burden with Clearwire (NASDAQ:CLWR) will certainly help operational efficiency, but just how long investors want to wait to get those last few cylinders firing -- and what price to pay for shares -- is much less certain.

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Fool contributor Dave Mock often feels like a four-banger living in an eight-banger world. Dave is the author of The Qualcomm Equation. Vodafone is an Inside Value recommendation. The Fool's disclosure policy knows that slow and steady wins the race.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.