88 runs bad when warm outside

just shoot me! ive a 1995 88 6 6 cyl ( the 3600 or 3800 i forget), 94000im in texas, when its like 50 degrees or below outside, the car runs "near perfect". when it gets warmer outside, the engine jerks and looses power under load-even idling at like 45 or 50 mph itll jerk put if i floor it, it will go fast, but jerk while going.: ie holding the break down and flooring it produces sputtering, very low rpm..this is an outside temperature related issue. no codes present,also will backfire and a mechanic i visited said i should give it a tune-up. although that may help, i dont belive thats the problem. i believe its a sensor related to measuring the outside air pressure or temp. ive replaced the fuel filter, put berrymans in the tank. its got to be a simple problem.
please and thank you