Trooper Hesitation

I have a 2001 Trooper with 70K miles. It hesitates around 40-45 mph. I have had the fuel system cleaned, replaced plugs, replaced the fuel filter, & air filter but no help. For a while when I switched from regular to mid-grade gas it fixed the problem but now it is doing it again. Also, when I use gas additives it seems to help for about a week or two at the most. I was wondering if anybody has run into this problem or have any suggestions? Thanks.

Are you getting a check engine light? A couple total guesses could be EGR or intake manifold gasket related.

G/luck
Joel

EGR looks like. I replace mine and cleaned the intake with BG cleaner. Also you might want to replace the PCV valve. You can get AutoZone to read your computer codes. Good luck