Hesitate & miss when warm. Guess ?

My 95 wagon starts right up & runs fine when cold. But once it warms up, I get a bad miss or hesitation.
It's like one or more cylinders are not firing or producing any power. Any advice ? TIA.

Do you have any codes?

Could be as simple as a bad coolant temperature sensor. Or as nasty as a failing optispark module. Codes can be a guidance, but sometimes a problem is not quite bad enough to set a code. You may need a scan tool to look at the raw data. Some things (like the temperature sensor) you can hunt down with a multi-meter and the expected values from the Factory Service Manual, but the scan tool can be a real time saver even then.

Don't have a code. Haven't hooked up my scanner. Haven't dragged out my FSM & studied all
the steps needed to diagnose the problem. I was just hoping for a lucky shot. I need to clear out
my garage & get things set up before I can make a serious methodical effort to fix all of the
problems with the wagon. I think the reverse on the 4l60e is also slipping badly.

how about oxygen senors? If it runs ok in open-loop but poorly when in closed-loop mode, that may be the cause. The OXS is one of the primary inputs in closed-loop mode.

Sounds like mine last summer. Found out the timing was off. After I spent over hundred on new parts.