Lost 150-175 miles to the tank in under 10 months!!!! HELP!!!

I purchased my 2000 Sport about 15 months ago and I have lost 150-175 miles to the tank. I have heard that it is the transmission, but the mechanic wants to charge me $200 just to tell me whats wrong with it...and it might not even be the transmission. Has anyone heard of this before. Please let me know. Thanks.

How many miles?When was last tuneup?Check engine light on?
Truck still run strong or seem slugish?4/6/8 cylinder

is it a 5spd or a slush box-if the later, you may have a torque converter issue...

It is a 4.0 litre V-6 auto...I just had a tune up about 5-6 months ago. When I first bought the truck, it was quick and resonsive when I got on the gas. Now, when I get on it, there is a slight delay to get the RPMs up, and it doesnt accelarate near as quick as it did. I dont do it much seeing as how my gas milage is so horrible. So I dont know what the problem is. I went to the dealership(not covered under warrenty...expired)and they want too much money right now just to run a diagnostic on it. So I need help from you guys. Do you think you know what it is?? Let me know....thanks

I got 57000 miles on it and no I get no lights at all about anything. Well, I get a check gauge light, but thats for my oil pressure guage. Ever since I bought that, it jumps around all the time so its not reading anything...other than that, no lights...

I've got a 95 3.0 v6 & started getting poor milage & performance but my CEL came on. still haven't had codes read but replaced my 02 sensors & what a difference it made.i've heard to replace them every 50,000 miles & i've got around 150,00 never replaced them until now.i've got a 5speed so i don't know about an auto causing the problem. go to ranger sites where there may be more people with your problem.
rangerpowersports.com
the rangerstation.com
Good Luck

There are a few auto parts stores now giving "free" diagnostic services.....

i think Advance Auto is one of them

You probably have two problems - (oil pressure guage jumping) could be the sending unit or oil pump. (poor mileage) probably 02 sensors
Good luck