Once you check the big three...Fuel, Air and Spark start looking at the Vac lines and the thermo-switch. If you have a cracked or leaking vac line on one side of the thermo-switch after if warms up you could be getting a vacuum leak. Lack of vacuum causes everything from cutting out to lack of power. The vac lines like to crack on the underside where they attach to the nipple. The thermo-switch is the two port one, the thermo-valve is the five port one.

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98 Montero with cold weather package
96 Toyota Land Cruiser, fully locked Mall Machine :-)