Lack of power

[reb155]

I have a 92 V6 4runner it drives & goes well on normal driving but when cruising or
towing at 100kph (62mph) and I go up a hill I loose power and have to keep going down the gears the catalytic convertor is OK Computer Diagnostic is OK Fuel pressure is 42psi has anyone had this problem HELP

 

[fourwd1]

Stock tires or bigger tires ?

 

[Samuel]

what are you towing?

 

[reb155]

lack of power

towing a poptop caravan weight is 1900lb
or 870kg the problem is there towing or not towing