5.3 problems when > 98degrees outside?

[five0_4tluv]

i've been noticing the last few weeks that if my truck has been outside in the heat all day (>98 or so), that it acks differently than morning driving or <98 degrees. i've taken my truck in before because it seemed it wasn't shifting at the right rpm's, but they said it was within range. the issue when it's hot outside is that it sounds like the engine is struggling and rpm's are high. but in reality nothing is happening except a sometimes slight hessitation on acceleration and just crusing from a stop to about 30mph sounds like the engine is 3-4k rpm, but shifts at about 2k. if i'm driving home (@20-30 minutes) and pull into the garage i can smell a burning ever so slightly, like a house or something. can't find anything obvious under the hood.

 

dealer suggest catalytic converter clogged or going out. any suggestions or something to try.

 

thanks

[Haulin' 8.1]

I would check for a sticking fan clutch and excessive belt glazing from pulling it up locked.

 

Vernon