On first start of day, acceleration is sputtering with hard shift into 2 nd, hesitation when pedal depressed,etc. Once warmed up after about 10 minutes symptoms disappear & engine runs fine. Glow plugs were replaced 15,000 miles ago without any problem. Just finished 2 weeks of trips through 100 degree temps. At least it waited for me to get home before this,although at one point on trip I felt the problem,but once on the highways & operating temps reached (easily !) no problem.
My feeling is something in fuel system. Any advice & where to look ?

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06 CDI diesel fitter
96 E 300 D (sold but still chuggin)
87 300d (sold)
87 300TD (sold)
01 ML 320 (what was I thinkin?)