gas mileage - help!

Please help. MPG is down to 13 and that's interstate travel. Did have MPG of 19-20 so, what can I do? Any suggestions? Thanks.

what year?

http://www.geocities.com/endre_rl/isuzufaq.htm#faq8

99 Trooper. Ideas? Fuel filter is new, couple of new gaskets, mileage was bad before these were changed, and the MPG went up for about 2 days and then back down.

Clean the EGR, EGR port, PCV,

Fuel injectors. Check your tire pressure.

Thnx. Ive been thinking it might be the EGR as a cpl of times I have had to have it cleaned. I do ck tire pressure as I learned w/other cars how that affects MPG. Thanks much for your suggestions. I don't know what PCV is, but I'll ask a mechanic to ck it out for me. So far mechanics haven't known what to do not just for this but other problems. And I now live many hrs from a dealer. So . . . thanks.

Quick question, Do you clean the EGR valve or replace it? I called the auto part store they told me it cost $110.99 is this about right? And if you clean them what do you use to clean them with?

99% of the time they only need to be cleaned with standar carb cleaner.