97 V-6 3.8 LaSabre engine hesitation at 40

Engine hesitates (slips, lugs?) at 40 mph (shift point?). The dealer says it's the trans valve body (per a service bulletin). The trans shop (twice) says no way, trans is good and lock-up converter is good. He says it's a tune-up. Tune-up shop says it may be a fuel pump but he's not sure. Anyone have a known fix? Dealer- Petre; Trans shop- TriCity; Tune-up shop- Salem Boys (all Phoenix area). No check engine light- ever.

Try the spark plugs, that can cause a delayed gear change.

I would say you have a trans problem. If you had a misfire the check engine light would come on setting a code P0300 in the computer. Since you don't have a SES light on and that trans is known for this problem. I have changed many PWM solenoids inside for a shudder.

My concern is that there is a lot of diagnosis going on with no checking of these issues. There are ways of checking these possibilities, the GM manual is full of them, I have others from my experience. The first method is to confirm the problem. There have been oodles of complaints at these speeds, all typically revolving around the TCC (Torque convertor clutch). These engines are typically bulletproof. Just because there are no codes, doesn't mean that there no problems. Since you are seeking answers, find a shop willing to ask the correct questions and go from there. I can help, but without having the vehicle to look at, diagnosis is difficult. I have done my share of electronics work in my 40 years as a tech; I am sure I can assist any shop willing to look at it for you. Ray

I am having the same problem with "lugging" at at 40 mph. I have 50K miles on her. I don't think that there is a blown or cracked cylinder, because the engine is quiet and it doesn't vibrate at all. Why is she hesitating on me?