94 PA: Hesitation when accelerating

Hi! About three months ago I relocated from Houston, TX to Tucson, AZ, and drove my 94 PA. Upon making it to El Paso, TX I was at a half tank of gas and I notice the car starting hesitating when I would accelerate to 45 miles and over. So I topped off and it stopped. It started hesitating again at a half tank of gas on my way to Tucson. Before the trip I had the car tuned up. I was wondering was it bad gas. About a week ago I drove the PA to Phoenix and no hesitation when I would accelerate over 45 miles or more. Through the city it doesn't hesitate, even below a quarter tank of gas. But everytime I'm on the highway, when it gets near a half tank it starts to hesitate. It feels like fuel obstruction. I was wondering should I clean the fuel tank. If so, do you have any tips on doing so?

SSL

Please help.

I assume that you have changed the fuel filter recently. If not, you should do so, then check the fuel pressure @ idle. It should be 45+ @ idle and when you accelerate rapidly, it should drop 6-8 psi and then return to idle pressure when you let off.

Thanks HotZ28 (http://www.automotiveforums.com/vbulletin/member.php?u=297374) for replying. The last time I changed the fuel filter was a 1 1/2 years ago. I had the car tuned up then, also. Is time to change the fuel filter again? Also, how should I check the fuel pressure and what area of the car, do I need any gauges or tools and is there a certain method to do this?

Thanks for your help.