Had a nice flight on a PIA 747-200B with P&W engines from Dubai to Heathrow, great food if I recall. It was boiling in Dubai and we flew with the nose in the air at about 2,000 ft, barely accelerating and not climbing at all. We crossed the city and kept going for ages with the flaps still at the take-off setting. Felt like we were hanging in midair by a thread. I guess it was the heat but I had a similar experience in a three-quarters empty P&W powered Virgin 747-200 out of Gatwick so maybe the type is a little underpowered compared to the 777 et al (see the 'twins vs quads' argument about thrust:weight ratios).
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz