If it is TPS equipped, check & adjust per 4Crawlers web site instructions. Its amazing what this little piece of plastic can do. It sometimes does not set code, & will malfunction hot or cold & will effect other or be effected by other faulty sensor readings. It will sometimes be a intermittant problem & will be hard to diagnose. This is a very sensitive sensor. Just a guess. But i have had similar problems. Especially after doing any fuel system maint. or removal of such.

85 4runner, 22re,cam, headers,2.25free flow exhaust,3"susp lift, 33's,custom bumpers,& stuff