'89 300te won't start when hot

[ythraccm]

Engine starts fine when cold. After running for 15 minutes or longer starts idling rough and slightly erratic at which time sudden acceleration while parked causes engine to run rough momentarily and then smooth out at higher revs.
It will not start again until it cools down although sometimes it will backfire.
Once cold it will start again and follow the same sequence.
Suspect the coil might be going bad but do not have resistance values for primary and secondary to check out. I get about 10.6K ohms seconday to primary terminal and 20k to ground and .8 ohms across primary terminals when warmed up. I believe the primary reading is 1.8 ohms when cold. I have to recheck.

[ozzy]

Could be the thermolator.

[dpetryk]

Check the condition and strength of the spark when it runs good and then when bad. That will tell you is if is ignition related. It could be a number of ignition related components including coil, cap, rotor, wires, ignition module etc.