I have a 92 seville the car is 15 years old she's lost a lot of power and she's suck a lot of gas. I want to know if I get the engine rebuild will it get it solve my problem. Or there's any other methods to go by. also do anyone know whats a good price to go by because I don't want to get rip off.

How many miles are on the car?

4.9s are great and very reliable engines. First figure out what is wrong (must be something very simple) before even thinking of rebuilding. Get the trouble codes.

^ like he said.

Pull the codes, it's gotta be something simple.

4.9's are the most reliable cadillac engine, on average you shouldnt need a rebuild until around between 210k & 250k and thats beating the hell out of it.

If you don't have any codes, even if you do, try some of the simple things, like checking spark plug gap, check cleanliness of air filter, and make sure your vacuum lines are not cracked/leaking. After I purchased my used '94, I found the plug gap to be way larger than it was supposed to be. I corrected the gap and saw about a 3 mpg improvement.

Simple is probably not real fair thing to say about checking the plugs. The back ones are a little difficult, but not impossible, to get out and back in.

Oxygen sensors.

Fuel Pressure Regulator

Check The Tps