Right now the problem we are having with the coach is excessive play in the steering wheel which makes driving a chore. Folks on another forum suggest I go to a reputable truck place and have the alignment checked and consider a steering stabilizer. That is on tap for next week.
I replied to you on the other forum, copying it here too.
Hi Paula, It's me Ron Dittmer from the Cruisers forum.
Your Phoenix Cruiser 2551 at 26'-5" long, 93" wide, and 10'-1" to the top of a/c unit, built on an E450 chassis is a lighter weighted house on the heaviest duty chassis and drive train available anywhere. Most motor homes using the E450 chassis are taller, wider, longer, and heavier. My point being, you have a lot of margin considering weight and engine power.
As other Ford 1998-2010 E350 and E450 owners say about their own Ford V10 engine, it's strong, but it's also very noisey when going up inclines. You may think it's working hard, but by Ford's design, it spins very fast to get up hills. Do not be concerned about it. You'll simply have to get used to hearing the engine reving as a normal thing. The same when going down hill. When I do engine braking down-hill, the engine revs way up too, sometimes near red-line on the tachometer. For a little "extra" peace of mind, I now use full synthetic motor oil.
About your PC-2551 handling issues. You sound like me when we bought our PC-2350. As others above here stated, and yourself confirmed, take it to a truck suspension shop, not an automotive suspension shop. If you have limited funding for suspension upgrades, then you will want to do improvements one step at a time. I advise to consider evaluating/upgrading in this order.
1a) Tire pressure is very influential in handling and quality of ride. Tire pressure is determined by the weight on it. Ask Phoenix USA what the weight is on front and rear tires, then follow the chart in Michelan's website on pressure per weight.
1b) Front wheel alignment. Our 2007 PC-2350 alignment was off by so much that the truck shop had to use offset bushings to get the camber set properly. Phoenix USA may cover the cost of a wheel alignment. I heard them covering for another PC owner. Our front wheel alignment cost us $170 three years ago. BTW: The shop told me most motor homes require offset bushings for a proper alignment, so the Phoenix Cruiser is no exception.
When you take the RV in for a wheel alignment, fill the fresh tank with water, empty the waste tanks, and fill up the RV with a full tank of gas and propane. Also keep your gear, dishes, etc. inside. The mission is to get an alignment done with the RV weighted as it would be during a voyage. If you want to go an extra step, place weights just behind the driver and passenger seats to represent two adults in the front cab. I did that.
2) Replace your Ford steering stabilizer with a heavy duty one. We have a Safe-T-Plus and it does a great job. But there are other good brands out there too. Ours eliminates driver over-reaction and "steering wheel floaties".
3) Replace your shock absorbers with Bilsteins or Koni-RV shocks. The shocks on your E450 chassis could be the same used in the E350, and the E250 passenger and cargo van. That was the case in 2007. If true today, those shocks are not ideal for any motor home where the chassis is loaded to near capacity, 100% of the time because a house is always on it.
4) Replace your Ford rear stabilizer bar with a heavy duty one from Helwig, Roadmaster, or other brand. A heavy duty stabilizer bar significantly reduces side-to-side rocking motion like a boat on water.
5) Replace your Ford front stabilizer bar for the same reasons.
6) If you tow anything at all, you might find the rear end of your PC-2551 moving side to side horizontally, commonly referred to as "tail-wagging". If so, then consider a rear trac bar. That will eliminate that unwanted motion.
We had all this done at once, costing us $3900. It was a lot of money to spend, but given the experience addressing handling issues with our old RV of 24 years, I wasn't going to fool around this time to try and save some money. We decided to do it all at once, be done with it, and enjoy this "perfect handling" RV from DAY ONE. Our PC-2350 handles like a dream. And it tows a vehicle 100% of the time too.