I need help with my climate control on a 87 300 SDL. It is cycling too hot for set temp and then turning on AC to cool down, then getting too cold, turning on heat and so on. Big temp swings I cleaned the temp sensor and checked for draw from aspirator pump and it seems ok (held tissue to sensor grille) What next?

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87 300 SDL 278,200
85 380 SL 126,400
assorted domestic crap
79 240 D (sent on)