My 1986 t-type sputtering on normal hot temp but runs good before it gets to 180 degrees.

[86ttype510]

hi everyone i have 1986 buick t-type all stock and currently having a sputtering problem when it gets to normal hot temp. For an example if i turn the vehicle on and warm it up for 5 min. take off it runs excellent
once it gets to 180 degrees on my temp gauge it starts sputtering back firing but never turns off on me. What i did noticed that if my lights are on (headlights) it runs better and wont get that sputtering as much as it was before i turned them on. I could say it takes the sputtering like 80-90% . I really dont know where to start tracking down the problem. I would appreciate any information and help regarding my problem thankyou.

 

[mikestertwo]

Ignition module, crank sensor?

 

[mikestertwo]

What is your ignition voltage reading when the sputtering starts?

 

[86ttype510]

I don't know what's my voltage but what i did was drove the car around till it started sputtering and then i disconnected the plug that goes into the alternator and drove it around and it was worst sputtering way way more than usual. The reason i did that was because of i turn on my headlights my sputtering stops for about 80% of the usual. ... I don't know if my alternator coil pack or ignition control module is bad. ... Any suggestion on Wat to do next? ???