When going 55 miles an hour on an incline the car starts to chug

I think I'm going to try the catalytic converter first but a tune-up sounds like it's probably in order to so thank you very much for your answer it's very muchly appreciated... of course that still doesnt excuse the fact that it still does need a tune-up LOL

Spark plug wire(s) breaking down under load is the most logical and common reason for this problem.. Can easily be tested to confirm.. Testing is the key word here so you don't blow a bunch of money on needless parts and repair!

Hmmm... Ok well I will definitely get the spark plugs checked then thank you

Thank you very much... That's one thing we hadn't thought of... you know where your mind goes when something like that happens goes to the most expensive answer and then to the cheapest answer there is no in between so I really appreciate that thank you