A "Bad Crank Sensor and it will cost around $500 to fix?

The first thing to do would be to check the fuel pressure. If it is low then, the fuel pump has probably failed. It is always a good idea to exhast the least expensive possibilities first because if you go and spend $500 for something that doesn't fix it, you'll be kicking yourself. Have them run a fuel pressure test first.

This post is 16 years old, so I think it's safe to assume the problem has been solved. Unfortunately, as happens too often, no one bothered to follow up with the solution or the steps involved in finding the cause to help others in the future. A lot of other steps were missed. The very first one should have been to read and record any diagnostic fault codes. Too many people think the Check Engine light must be on for there to be fault codes, but that is not true. Beginning with '96 models, there are over 2,000 potential codes in Engine Computers. Only about half of them refer to things that could adversely affect emissions. Those are the codes that turn on the Check Engine light. The other codes can be set but the light won't be on.

The next concern is to be aware diagnostic fault codes never ever say to replace a part. They only direct us to the circuit or system that needs further diagnosis. When a part is referenced in a fault code, that part is the cause of that code only about half of the time. First we have to rule out wiring and connector terminal problems, and mechanical problems associated with that part.

To further complicate this issue, it is not uncommon for a camshaft position sensor or crankshaft position sensor to fail without there being a related fault code set. This occurs more often when someone disconnects the battery in a misguided attempt at "resetting" something. Doing so erases any fault codes. After that, a defect with either sensor may not be detected simply from cranking the engine, so now that valuable information has been lost. Fault codes should always be read first. Cam and crank sensors often need more time for a failure to be detected, as in when a stalling engine coasts to a stop.

On most vehicles of this era, fuel pressure wasn't monitored, so there would never be a fault code related to that. Only a manual test would show if fuel pressure was low.

As for the original question, it is apparent replacing the crank sensor is an extremely difficult job because the standard "flat rate" time is 2.4 hours with no AC, and 2.8 hours if it does have AC. At that time shops typically needed to charge over $75.00 per hour to cover all their expenses, so figure on around $200.00, but that's just to replace the sensor. There's no way to magically know it is defective, especially if this was an intermittent problem. Those need a lot more time to make a definite conclusion before we waste a customer's money on the part. Diagnostic time can easily be another one or two hours, then there's the cost of the sensor.

Remember too, this was just an estimate. Some less reputable shops give low estimates to get the job over their competitors, then find other things to charge for later. Better shops calculate the expected cost, then add a considerable amount to cover any hidden unknowns that pop up along the way. Later they surprise their customers with a final bill lower than expected.

Here's links to some articles that may be useful:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.2carpros.com/trouble_codes/obd2